Principles of preparation and distribution in volumetric analysis. Preparation of titrations of sulfuric and hydrochloric acids

GAPOU LO "Kiri Polytechnic College"

Methodical handbook for witchcraft

MDK.02.01 Basics of sample preparation for different concentrations

240700.01 for the specialty chemical analysis laboratory assistant.

Rozrobila

Vikladach: Rozpovidova V.V.

2016 r_k

Zmist

stories

Rozcini

3-15

Rozrahunki when preparing salts and acids

Change of concentration from one type to another.

Mixing and dilution of divisions.Law of mixing of divisions

Techniques for preparing dishes.

15-20

Preparation of different salts

Preparation of dissolving acids

Preparing the basics

Technique for significant concentration of damage.

21-26

The concentration determined by densimetry

The concentration values are titrimetric.

Six rules of titration.

Umovi titrimetrically determined concentration of speech

Preparation of titrated

Establishment of titration

Calculation in volumetric analysis.

26-28

ROZCHINI

The concept of division and discord

As is clear, and in general, the main analysis is carried out at different intervals. Call the vikoryist name “rozchin”, we are respectful of the rightful rozchin. In active cases, the resin is separated from the vicinity of the molecules or ions, which is divided into the middle of the molecules of the agent.Rozchin- a homogeneous (uniform) sum that consists of particles of disintegrated speech, the originator and the products of their interactions.When a solid substance is broken up in water or to another breaker, the molecules of the surface ball pass from the breaker and, as a result of diffusion, are distributed throughout the entire volume of the breaker, then the breaker goes to a new ball of molecules, etc. At the same time, the return process begins with the breaker c - vision of molecules at different rates . The greater the concentration of destruction, the greater the peace of mind this process will be. With the increasing concentration of speech, without changing other minds, we can reach the point where in one hour there are as many molecules of broken speech as there are broken ones. This kind of outrage is calledwe will rape. If you would like to add a small amount of broken speech, you will lose the unbroken one.

Rozchinnist- the creation of speech is created with other speeches of the same system; - Discuss what words are found in the appearance of large atoms, ions, molecules and particles.The quantity of speech among the afflicted people meansdisorganization speak for the given minds. The diversity of different speeches varies among these and other communicants. A single piece of skin breaker can have a little more than a single amount of this speech broken out.Rozchinnist express a number of grams of speech in 100 g of wine in saturated wine at a given temperature. For the purpose of dispensing with water, the words are divided into: 1) good reasons (caustic soda, zukor); 2) low-grade (gypsum, Bertholet's salt); 3) practically indispensable (copper sulfite). Practically unintelligible speeches are often called unintelligible, although there are no absolutely unintelligible speeches. “Such speeches are called non-ordinary, the origin of which is extremely small (10,000 parts of the origin are divided into 1 hour of speech).

Please note that the breakdown of solids increases with temperature increases. How to cook when heated, close to stuffed, then shvidko, and then carefully cool it, it is created like thisintersections of differences. If you throw a crystal of broken speech into such a rift or mix it, the crystals will start to fall out. Therefore, the cooled wine will have more room, but it is less possible for the saturated wine at a given temperature. Therefore, when a crystal of disintegrated speech is added, all excess speech is crystallized.

The authorities of the robbers are always at odds with the authorities of the robber. It is necessary to boil at a high temperature, but not in a clean pot. The freezing temperature, for example, is lower for the retailer, lower for the retailer.

According to the character of the robber, the robberies are divided intowater and net. Until then, it is necessary to isolate substances from such organic agents as alcohol, acetone, benzene, chloroform, etc.

Most salts, acids, and salts are prepared in water.

Methods for expressing the concentration of disorders. The concept of gram equivalent.

The skin is characterized by the concentration of the broken speech: the amount of speech that is located at the singing amount of the broken. The concentration of substances can be expressed in hundreds, moles per 1 liter of consumption, equivalents per 1 liter of consumption and titer.

The concentration of speech products in different regions can be expressed in different ways.

The mass fraction of the split speech w(B) is a dimensionless quantity, which is similar to the ratio of the mass of the split speech to the final mass of the split m

w(B) = m(B) / m

or otherwise called:hundredth concentration rozchinu - is measured by the number of grams of speech 100 g of rozchinu. For example, 5% of alcohol is mixed with 5 g of alcohol per 100 g of alcohol, so 5 g of alcohol equals 100-5 = 95 g of alcohol.

The molar concentration C(B) shows how many moles of the dissolved substance are contained in 1 liter of dissolution.

C(B) = n(B) / V = m(B) / (M(B) V),

de M(B) is the molar mass of the dissolved resin g/mol.

The molar concentration is expressed as mol/l and is designated “M”. For example, 2 M NaOH is a bimolar solution of sodium hydroxide;Unimolar (1 M) dilutions include 1 mole of rheutin in 1 liter of dilution, bimolar (2 M) - 2 moles in 1 liter, etc.

In order to determine how many grams of a given substance are present in 1 liter of a given molar concentration, it is necessary to know itsI pray for masa, Tobto masu 1 mole. The molar mass of the speech, expressed in grams, is numerically older than the molecular mass of this speech. For example, the molecular weight of NaCl is 58.45, and the molar mass is also 58.45 g. Thus, 1 M NaCl is mixed with 58.45 g of sodium chloride in 1 liter of solution.

The normality of a word means the number of gram-equivalents of a given word in one liter of wine or the number of milligram-equivalents in one milliliter of wine.
Gram equivalent speech is called the number of grams of speech, numerically equal to its equivalent.

Equivalent to collapsible speech - call such a quantity that in this reaction it is equivalent to (equivalently) 1 mole of water.

The official of equivalence is designated:

1) the nature of speech,

2) a specific chemical reaction.

a) in metabolic reactions;

ACID

The size of an acid equivalent is determined by the number of water atoms that can be replaced by metal atoms in the acid molecule.

butt 1. Significant equivalent for acids: a) HCl; b) N 2 SO 4 , c) N 3 RV 4 ; d) N 4 .

Decision.

a) E = M.M/1

b) E = M.M/2

c) E = M.M/3

d) E = M.M/4

For different rich base acids, the equivalent occurs in a specific reaction:

A)H 2 SO 4 +2KOH→ K 2 SO 4 + 2H 2 O.

In this reaction, two atoms of water are replaced in the sulfuric acid molecule, therefore, E = M.M/2

b)H 2 SO 4 + KOH→ KHSO 4 +H 2 O.

And here the sulfuric acid molecule is replaced by one atom of water E = M.M/1

For phosphoric acid, depending on the reaction, the value is a) E = M.M/1

b) E = M.M/2 c) E = M.M/3

BASICS

The base equivalent is determined by the number of hydroxyl groups that can be replaced by the acid residue.

butt 2. Significance equivalent of the basics: a) KON; b)Cu( OH) 2 ;

V)La( OH) 3 .

Decision.

a) E = M.M/1

b) E = M.M/2

c) E = M.M/3

SOLI

The salt equivalent values are indicated by the cation.

The value is divided by M.M. some salts are olderq·n , deq - Charge to the metal cation,n - The number of cations in the salt formula.

butt 3. Significant equivalent of salts: a) KNO 3 ; b)Na 3 P.O. 4 ; V)Cr 2 ( SO 4 ) 3;

G)Al( NO 3 ) 3.

Decision.

A)q·n = 1 b)1 3 = 3 V)z = 3 2 = 6, G)z = 3 1 = 3

The values of equivalence factors for salts are also

reactions similar to those for acids and bases.

b) in oxide-oxide reactions for business

equivalent to a vikoryst electronic balance circuit.

The amount of yak responsible for the buti is divided by the M.M for speech at times equal to the number of electrons accepted and given by the speech molecule.

Before 2 Cr 2 O 7 + HCl → CrCl 3 + Cl 2 + KCl + H 2 O

for direct 2Сr +6 +2·3e →2Cr 3+

reaction 2Cl - - 2 1e →Cl 2

for gate 2Cr+3-2 3e →Cr +6

Cl2-2 reactione →2Cl

(K 2 Cr 2 O 7 )=1/6

(Cr) = 1/3 (HCl) = 1 (Cl) = 1) (Cl2) = 1/2 (Cl) = 1

The normal concentration is indicated by the letterN (In rose formulas) or with the letter “n” - at the specified concentration of this substance. If 1 liter contains 0.1 equivalents of speech, the wine is called decinormal and is designated 0.1 n. A dose that contains 0.01 equivalent of speech in 1 liter of dose is called centinormal and is designated 0.01 n. The fragments are equivalent to that many words in this reaction. suggests 1 mole of water, obviously, the equivalent of any other speech is responsible for this reaction. And this means thatIn any reaction, speeches react in equivalent quantities.

Titrated call divisions, the concentration of which variescaption, i.e., a few grams of liquid, divided into 1 ml. It is very common in analytical laboratories to titrate the difference directly to the substance that is indicated. TogSo The dose titer shows how many grams are indicated in 1 ml of this dose.

To prepare samples of molar and normal concentrations, the liquid is weighed in analytical containers, and the samples are prepared in a still flask. When preparing concentrated acids, it is necessary to measure the concentrated acid with a burette and a glass tap.

The requirement is to be corrected with accuracy to the fourth tenth decimal place, and molecular weights are taken with the accuracy indicated in the subdivision tables. The volume of concentrated acid is adjusted to the nearest tenth place.

When prepared at different percentage concentrations, the reagent is dissolved in techno-chemical thereses, and then mixed with a still cylinder. Therefore, the volume of the liquid should be adjusted to an accuracy of up to 0.1 g, and the volume of 1 volume with an accuracy of up to 1 ml.

First of all, before preparing the rosemary, it is necessary to create a mixture in order to extract the quantity of the mixture that is being prepared, and the container for preparing the mixture of the mixture at a given concentration.

Rozhrakhanki at the time of preparation of salts

Example 1. You need to prepare 500 g of 5% potassium nitrate. 100 g of this mixture, mix 5 g KN0 3 ; Let's add up the proportion:

100 g rozchinu-5 g KN0 3

500" -X » KN0 3

5 * 500/100 = 25 rub.

You need to take 500-25 = 475 ml of water.

Example 2. You need to prepare 500 g of 5% CaC solutionIFrom salt CaCl 2 .6N 2 0. First of all, it is necessary to dissolve waterless salt.

100 g rozchinu-5 g CaCl 2

500 "" -x g CaC1 2

5 * 500 / 100 = 25 g

Molna masa CaCl 2 = 111, molar mass of CaCl 2 6H 2 0 = 219. Otje,

219 g CaCl 2 *6Н 2 0 revenge 111 g CaCl 2 . Let's add up the proportion:

219 g CaCl 2 *6Н 2 0 - 111 g CaCl 2

X » CaС1 2 -6H 2 0- 25 "CaCI 2 ,

219 * 25 / 111 = 49.3 rubles.

The volume of water remains 500-49.3 = 450.7 g, or 450.7 ml. Since water is measured with a peaceful cylinder, ten parts of a milliliter are not taken into account. Now you need to add 451 ml of water.

4. Dehydration during preparation of acids

When preparing acid solutions, it is necessary to boil so that the acid concentration is not 100% and discard the water. In addition, the required amount of acid should not be dissolved, but mixed with a peaceful cylinder.

Example 1. You need to prepare 500 g of 10% hydrochloric acid, with a clear 58% acid, strength d=l,19.

1. We know the strength of pure chloride water, which is present in the prepared acid solution:

100 g rozchinu -10 g NS1

500 "" -X » NS1

500 * 10/100 = 50 g

To differentiate between percentage concentrations, mole mass should be rounded to whole numbers.

2. We know the number of grams of concentrated acid, which contains 50 g of HC1:

100 g acid-38 g HC1

X » » - 50 » NS1

100 50/38 = 131.6 g.

3. We know the volume occupied by this volume of acid:

V= 131,6 / 1,19= 110, 6 ml. (rounded to 111)

4. The volume of water (water) is still 500-131.6 = 368.4 g, or 368.4 ml. If the required amount of water and acid is mixed with a peaceful cylinder, then ten parts of a milliliter should not be taken. Also, to prepare 500 g of 10% hydrochloric acid, you need to take 111 ml of hydrochloric acid and 368 ml of water.

Example 2. When preparing acids, make sure to use standard tables that indicate the amount of acid, the thickness of the acid, the thickness of the acid, and the number of grams of acid that can be contained in 1 liter of the concentration. atsii. And here the little one will say goodbye. The strength of the acid that is being prepared can be used for singing.

For example, you need to prepare 500 ml of 10% hydrochloric acid from concentrated 38% hydrochloric acid. From the tables we know that 10% hydrochloric acid contains 104.7 g of HC1 in 1 liter of solution. We need to prepare 500 ml, so the solution has 104.7:2 = 52.35 g of HCl.

It is calculable how much concentrated acid is needed. According to the table, 1 liter of concentrated HC1 contains 451.6 g of HC1. Let's add up the proportion:

1000 ml-451.6 g HC1

X ml - 52.35 "NS1

1000 * 52.35 / 451.6 = 115.9 ml.

The volume of water is still 500-116 = 384 ml.

Also, to prepare 500 ml of 10% hydrochloric acid, you need to take 116 ml of concentrated HC1 and 384 ml of water.

Example 1. How many grams of barium chloride are needed to prepare 2 liters of 0.2 M solution?

Decision. The molecular weight of barium chloride is 208.27. Otje. 1l 0.2 M Rozchinu is guilty of revenge 208.27 * 0.2 = = 41.654 g VaSI 2 . To prepare 2 liters you need 41.654 * 2 = 83.308 g of calciumI 2 .

Example 2. How many grams of anhydrous soda Na 2 C0 3 You will need to prepare 500 ml of 0.1 N. Rozchina?

Decision. Molecular mass of soda 106004; equivalent weight of Na 2 C0 3 = M: 2 = 53.002; 0.1 eq. = 5.3002 rub.

1000 ml 0.1 N. revenge revenge 5.3002 g Na 2 C0 3
500X » Na 2 C0 3

x = 2.6501 g Na 2 C0 3 .

Example 3. A quantity of concentrated sulfuric acid (96%: d=l.84) required 2 l 0.05 n. the breakdown of sulfuric acid?

Decision. The molecular weight of sulfuric acid is 98.08. Equivalent mass of sulfuric acid H 2 so 4 = M: 2 = 98.08: 2 = 49.04 rub. Masa 0.05 eq. = 49.04 * 0.05 = 2.452 rub.

We know how much H 2 S0 4 may be reduced to 2 l 0.05 n. Rozchinu:

1 l-2452 g H 2 S0 4

2" -X » H 2 S0 4

X = 2.452 * 2 = 4.904 r H 2 S0 4 .

To calculate how much for this requirement you need to take 96% of the amount H 2 S0 4 Let's add up the proportion:

at 100 g conc. H 2 S0 4 -96 g H 2 S0 4

U » » H 2 S0 4 -4.904 g H 2 S0 4

Y = 5.11 g H 2 S0 4 .

We overindulge in this amount of money: 5,11:1.84=2.77

In this manner, for preparation 2 liters 0.05 n. For treatment you need to take 2.77 ml of concentrated sulfuric acid.

Example 4. Calculate the NaOH titer, as it is clear that its exact concentration is 0.0520 N.

Decision. It is worth remembering that the titer is called instead of 1 ml the volume of speech in grams. Equivalent weight of NaOH=40. 01 g We know how many grams of NaOH are contained in 1 liter of this product:

40.01 * 0.0520 = 2.0805 rub.

Mix 1 liter of 1000 ml.

T = 0.00208 g/ml. You can quickly calculate it using the formula:

T=E N/1000 g/l

deT - titer, g/ml;E - equivalent masa;N- normality is different.

Todi titration: 40.01 0.0520/1000 = 0.00208 g/ml.

Example 5 Calculate the normal concentration of HN0 3 It is clear that the titer of this fraction is equal to 0.0065. For breakdown, the following formula is used:

T=E N/1000 g/l, zvіdsi:

N=T1000/E 0,0065.1000/ 63.05 = 0.1030 stars

Example 6. What is the normal concentration of sodium, as it turns out that 200 ml of liquid contains 2.6501 g of Na 2 C0 3

Decision. How it was calculated at the butt 2: ENA 2 zi 3 =53,002.
We know how many equivalents there are to make 2.6501 g Na 2 C0 3 :
2.6501: 53.002 = 0.05 eq.

In order to calculate the normal concentration of the substance, we add up the proportion:

200 ml mix 0.05 eq.

1000 » »X "

X = 0.25 eq.

In 1 liter of this amount there will be 0.25 equivalents, then the amount will be 0.25 n.

For such a breakdown, you can speed up the formula:

N =P 1000/E V

deR - quantity of speech in grams;E - equivalent to the mass of speech;V - Volume of consumption in milliliters.

ENA 2 zi 3 =53.002, then the concentration of this substance is normal

2,6501* 1000 / 53,002*200=0,25

5. Change of concentration from one type to another .

In laboratory practice, it is often necessary to change the concentration of obvious differences from one unit to another. When changing the 100% molar concentration, it is necessary to remember that the 100% concentration is distributed in volume, and the molar and normal concentration is distributed in volume; therefore, for overconcentration it is necessary to know more there is a rozchina.

The strength is determined in the following tables or measured with a hydrometer. What is significant for us:Z - Vidsotkova concentration;M - molar concentration;N- normal concentration;d - The strength of the structure;E - equivalent masa;m - molar mass, then the formulas for conversion from percentage concentration to molar and normal concentration will be as follows:

Example 1. Yak molar and normal concentration is 12% of raw materialacids, alkalinityd=l.08g/cm?

Decision. Molar mass of sulfuric acid is ancient98. Sledchyale,

Yong 2 so 4 =98:2=49.

Submitting necessary valuesVformulas, omitted:

1) molar concentration12% The meaning of sulfuric acid is ancient

M = 12 * 1.08 * 10/98 = 1.32 M;

2) normal concentration12% rosemary acidmore ancient

N= 12 * 1.08 * 10/49 = 2.64 n.

Example 2. Yak percentage concentration 1 star. the strength of hydrochloric acid, the strength of which1,013?

Decision. MolnamasaNSImore than 36.5,well, Ens1 =36,5. Introduced formula(2) omitable:

C= N*E/10d

Also, percentage concentration1 n. The meaning of hydrochloric acid is ancient

36,5*1/ 1,013*10 =3,6%

Sometimes in laboratory practice it is possible to overestimate the molar concentration to the normal value. If the mass of speech is equivalent to the ancient molar mass (for example, KOH), then the normal concentration is the same as the ancient molar concentration. Yes, 1 star. The dilution of hydrochloric acid will be 1 M per hour. However, for most compounds, the equivalent mass is not equal to the molar concentration and, therefore, the normal concentration of these substances is not equal to the molar concentration. To convert from one concentration to another, we can use the following formulas:

M = (NE)/m; N=M(m/E)

Example 3. Normal concentration is 1M sulfuric acid Vidpovid-2M

Example 4, molar concentration 0.5 N. Rozchinu Na 2 CO 3 Vіdpovіd-0.25N

When converting the 100% concentration into a molar concentration, it is necessary to remember that the 100% concentration is distributed into mass density, and the molar concentration is normal - into volume, so in order to convert it you need to know the thickness of the mixture. What is significant: h – concentration; M – molar concentration; N – normal concentration; e - equivalent masa, r - thickness of the mixture; m - molar mass, formulas for conversion with percentage concentration will be as follows:

M = (s p 10)/m
N = (c p 10)/e

These formulas can be used quickly if it is necessary to convert the normal or molar concentration to a hundred percent.

Sometimes in laboratory practice it is possible to overestimate the molar concentration to the normal value. If the weight of the reagent is equivalent to the traditional molar mass (for example, for HCl, KCl, KOH), then the normal concentration is the traditional molar concentration. Yes, 1 star. The volume of hydrochloric acid will be 1 M per hour. However, for most compounds, the equivalent mass is not equal to the molar concentration and, therefore, the normal concentration of these substances is not equal to the molar concentration.
To convert from one concentration to another, you can use the following formulas:

M = (N E)/m
N = (M m) / E

6. Mixing and dilution of divisions.

As soon as the mixture is diluted with water, its concentration will change proportionally to the change. If the dilution volume increases twice, then its concentration will change twice. When several substances are mixed, the concentration of all substances that are mixed changes.

When two components of the same substance are mixed, but at different concentrations, a new concentration emerges.

If you mix a% and b% of the mixture, then you can remove the mixture from the % concentration, and if either a>b, then a>c>b. The new concentration is closer to the concentration of the substance that was taken more during mixing.

7. The law of mixing divisions

The number of mixing compounds is proportional to the absolute differences between their concentrations and the concentration of the compound that is highest.

The law of mixing can be expressed by a mathematical formula:

mA/ mB=S-b/a-s,

demA, mB- the number of components A and B taken for mixing;

a, b, c- depending on the concentration of components A and B that are removed as a result of mixing. If the concentration is expressed in %, then the number of products that are mixed must be taken from your units; When concentrations are taken in moles or normals, then the number of quantities that vary must be expressed in liters.

For relief, vikoristannyamixing rules stagnatecross rule:

m1 / m2 = (w3 - w2) / (w1 - w3)

For which, along the diagonal from a larger concentration value, raise a smaller value, hold (w 1 -w 3 ), w 1 > w 3 i (w 3 -w 2 ), w 3 > w 2 . Then we add up the relationship between the outputs and m 1 /m 2 and calculate it.

butt
Determine the mass of the output ingredients with the mass fractions of sodium hydroxide 5% and 40%, so that when they are mixed, the mixture is equal to 210 g with the mass fraction of sodium hydroxide 10%.

5/30 = m 1 / (210 - m 1 )
1/6 = m 1 / (210 - m 1 )
210 – m 1 = 6m 1
7m 1 = 210
m 1 =30 RUR; m 2 = 210 - m 1 = 210 - 30 = 180 g

PREPARATION TECHNIQUES.

If water serves as a source, it is necessary to distill only distilled or demineralized water.

First prepare a suitable container in which to cook and save household items. We clean the dishes. I am concerned that water stains may interact with the material of the dishes; the inside of the dishes is coated with paraffin or other chemically resistant substances.

Before preparing the items, it is necessary to prepare, if possible, 2 different vessels: one for preparation, and the other for storing the items. Vimit the vessel to be graduated in advance.

To dismantle the traces, vikorist use pure speech. Prepared orders must be checked against the required language and, if necessary, the orders corrected. It is necessary to use the mixture to protect the prepared materials from the consumption of saws and gases in them, which may cause acts of violence.

During the preparation and storage of food items, bottles or other containers that require high viscosity must be sealed with stoppers.

With particularly precise analyzes of the traces, it is important to take into account the ability of the glassware to harden, as it is acceptable, quartz dishes.

In this case, it is better to steal from porcelain dishes, rather than from glass.

1. Technique for preparing different salts.

Dissolution is approaching.

The ready-made waste is either filtered or allowed to stand in the form of small houses near the water, after which behind the help of a siphon a clear cut is added. It is important to check the concentration of the skin solution. The easiest way is to measure the thickness with a hydrometer and compare the calculated value with the tabular data. If the disintegration concentration is less than the specified one, the required quantity of the solid substance to be disintegrated is added. If the solution has a concentration greater than the specified one, add water and adjust the concentration to the required level.

Exactly break it up.

Precise salts are most often prepared for analytical purposes, and at a very normal concentration. Some of the exact results are not stable enough when stored and can be changed under the influence of light or acidity or other organic houses that are placed in the wind. Such exact findings are periodically verified. When using sodium sulfuric acid when standing, it is often necessary to avoid the loss of plastic sulfur. This is the result of vitality, especially of the type of bacteria. The production of potassium permanganate changes when there is light on them, a saw and a house of organic walking. The production of nitrate solution takes place during the hour of light. Therefore, there are large reserves of fine salts, unstable until stored, not a trace of the mother. The use of such salts is saved until the next day. The type of light changes according to:AgNO 3, KSCN, N.H. 4 SCN, KI, I 2, K 2 Cr 2 O 7.

2. Technique for preparing acids.

Most often in the laboratory, hydrochloric, acid and nitric acids are used. The laboratory needs concentrated acid; Vidrant instead of acids is designated as thick.

To prepare a flask with a volume of 1 liter, fill a 1-liter flask with distilled water (halfway), add the required volume of the liquid to the desired strength, stir, and then add the volume to a liter. When diluted, the flasks become more heated.

Precisely, they prepare the same way, vicoristic and chemically pure preparations. Prepare the mixture in a concentrated manner, then dilute it with water. The exact concentration is verified by titration with sodium carbonate (Na 2 CO 3 ) or acidic potassium carbonate (KHCO 3 ) and “correct”.

3. Techniques for the preparation of wild meadows.

The greatest compatibility is caused by caustic soda (NaOH). The stems from the hard tongue are prepared with concentrations of rosemary (approximately 30-40%). When broken, there will be a strong rupture. As a rule, the meadow is made from porcelain dishes. The next step is to initiate a civil war.

Then the vision is partly poured into another darkness. This capacity should be secured with a calcium chloride tube for removing carbon dioxide. To prepare the wine at an approximate concentration, determine the thickness using a hydrometer. Preservation of concentrations of ingredients in glassware is allowed if the surface of the glass is coated with paraffin, otherwise the glass is cured.
To prepare precise preparations, use a chemically clean meadow. The preparations are verified by titration with oxalic acid and corrected.

4. Preparation of worker's work from fixation.

Fixali- It is precisely important to use a number of solid, chemically pure substances, or to accurately measure the quantities of their substances, placed in a sealed ampoule bottle.

Fixals are prepared at chemical plants or in special laboratories. Most often the ampoule contains 0.1 or 0.01g-eq speech Most fixings are well preserved, but their parts change over time. Thus, after 2-3 months, the formation of acidic meadows becomes unstable due to the interaction between the meadows and the ampoule.

To prepare the mixture from the fixan, instead of the ampoule, carefully transfer it to a beaker, dilute the mixture with distilled water, bringing it to the mark.

Apply it in this way: the strikers, which are in the box with fixan, wash the head with tap water, and then with distilled water. Insert one striker into a clean chemical shower 3 in such a manner that the long end of the striker fits into the pipe of the sprayer, and the short end of the other direction burns out; The cross-like surface of the striker rests against the lower part of the virvy body. Insert the virus into a clean peace flask at once.

Wash the ampoule with warm, and then with cold distilled water, so as to crease the label and become clogged. The bottom of a well-worn ampoule is struck (where it becomes jammed) against the striker of the vial and the bottom of the ampoule is broken. The position of the ampoule does not change over the watering can or the other striker break through the top corner of the new one.

Instead, the ampoule floats (or dries) in a beaker. Without changing the position of the ampoule, at the top opening, once closed, insert the end of the rinsing tube drawn into the capillary and rinse the ampoule from the middle with a strong jet. Then, using a jet of water from a washing machine, thoroughly rinse the outer surface of the ampoule and the spout with the striker. After removing the ampoule from the spoon, bring the rhubarb in the flask to the mark. Close the flask tightly with a stopper and carefully mix the ingredients.

TECHNIQUE FOR ULTIMATE CONCENTRATION OF ROZCHINS.

The concentration of rheutin in the region is determined by densimetry and titrimetric methods.

1. Densimetry is used to measure the strength value of the product, knowing how to calculate the % concentration in the tables.

2. Titrimetric analysis is a method of liquid analysis, in which the acidity of the reagent, consumed during the chemical reaction, is measured.

1. The concentration is determined by densimetry. Understood gustini

Thickness is a physical quantity, which is determined by the mass of one word. For a non-uniform speech, the thickness at the singing point is calculated as the ratio of body mass (m) to its volume (V), when the volume is reduced to this point. The average thickness of heterogeneous speech is m/V.

The strength of the speech lies in the mass , from what it is folded, and the strength of the packagingatomsand molecules in speech. How big is the mass?atomsthe more powerful it is.

Types of density and units in the world

Thickness varies in kg/m³ for the CI system and g/cm³ for the SGS system, others (g/ml, kg/l, 1 t/ ) - depart.

For dry and porous bodies, separate:

- correct thickness, which is indicated without emptying

- There is a strength that is realized as the relationship of the mass of speech to every volume that deals with it.

Duration of thickness depending on temperature

As a rule, with a change in temperature, the thickness increases, and substances whose thickness is different, for example, water, bronze andchavun.

Thus, the thickness of water reaches its maximum value at 4 °C and changes with both increases and decreases in temperature.

2. Varying concentration titrimetric analysis

In titrimetric analysis, it is possible to react in two ways and to more accurately determine the moment of completion of the reaction. Knowing the concentration of one substance, you can determine the exact concentration of another.

The cutaneous method has its own working functions, indicators, and there are similar types of problems.

Depending on the type of reaction that occurs during titration, there are several methods of volumetric analysis.

The most common ones to argue with are:

1. Neutralization method. The main reaction is the neutralization reaction: the interaction of an acid with a base.
2.Method of oxidimetry, which includes methods of permanganatometry and iodometry. It is based on oxidation-renewal reactions.
3.Settling method. The basis is the reaction of the creation of small-scale actions.
4.Method of complexonometry - on the illumination of low-dissociation complex ions and molecules.

Basic concepts and terms of titrimetric analysis.

Titrant - according to the reagent at a given concentration (standard dose).

Standard rozchin - The method of preparation is divided into primary and secondary standard conditions. The first one is to prepare the exact quantity of pure chemical speech from the singing quantity of the dispenser. The second one is prepared approximately at the concentration and is determined to be the same concentration as the first standard.

Equivalence point - the moment when the given duty of the worker has a quantity of speech equivalent to the quantity of the assigned speech.

Meta titration - more precisely, the variation of the volumes of two categories, in which there is an equivalent volume of speech

Direct titration – complete titration of song “A” with titrant “B”. This is a problem because the reaction between “A” and “B” proceeds smoothly.

Scheme of titrimetric analysis.

To carry out titrimetric measurements, standard (working) procedures are required to determine the exact normality and titre.
Such orders are prepared for precise measurements or approximate, or even exact, concentrations to establish titrations, vicoristics and differences in the instructions of the formulas.

For acids, the following solutions are: sodium tetraborate (borax), sodium oxalate, ammonium oxalate.
For meadows: oxalic acid, succinic acid

The preparation of rosemary includes three stages:
Rozrakhunok hanging
Take the hang
Rozchinennya hanging
When the concentration is established for precise measurements, it is important for analytical purposes.

If the concentration can be set by precise measurements, it can be taken on technochemical devices, and in rare cases it may reduce the cost of insurance.

To determine the exact concentration, titration is carried out, which assumes that two factors react with each other and a point of equivalence is fixed using an additional indicator.

The concentration of one of the disorders (robotnik) is definitely visible. As a rule, it is placed in a burette. Another dose with an unknown concentration is selected from the final flask with a pipette in strictly precise steps (pipetting method), or the precise hanging is determined from a sufficient number of pipettes (several hanging method). An indicator is added to the skin flask. Carry out titration at least 3 times until the results converge, the difference between the results should not exceed 0.1 ml. The breakdown of the analysis results will end. The most important point is to fix the point of equivalence.

Six rules of titration .

1. Titration is carried out in final glass flasks;

2. Instead of the flask, stir with wrappers, without lifting the flask from the back of the burette.

3. The extended end of the burette is located 1 cm below the upper edge of the flask. The rhubarb in the burette is set to zero before cutaneous titration.

4. Titrate in small portions – drop by drop.

5. Titration is repeated at least 3 times until similar results are obtained with a volume of no more than 0.1 ml.

6. After completing the titration of the sections, carry out 20-30 seconds to allow any liquid that has accumulated on the walls of the burette to drain off.

Umovi value of the titrimetric concentration of speech.

In volumetric analysis, the main operation is to measure the volume of two mutually related factors, one of which is the location of the speech that is being analyzed, and the concentration of the other is out of sight. The unknown concentration of the analyzed substance is determined by knowing the relationship between the obligations of the reacting substances and the concentration of one of them.

To successfully carry out a volumetric analysis, it is necessary to train the following minds:

The reaction between the substances that react must go to the end and proceed smoothly and quickly.

Since, during titration, it is necessary to accurately establish the moment of equivalence or fix the point of equivalence, the end of the reaction between the factors is due to the change of the dissolved substance or the appearance of a precipitated precipitate.

To establish an equivalence point during volumetric analysis, often freeze the indicators

The concentration of production of one of the divisions (working division) may be visible. Other speeches that find their place in discord are not guilty of influencing the main reaction.

Preparation of standard items.

1. Preparation of titrated punishment for the exact importance of the exit speech

The main part of volumetric analysis is titration, orstandard- The level of the output reagent, when titrated, is indicated instead of the value in the analyzed value.

The simplest way to prepare the rosemary is precisely at the required concentration, then. characterized by a clear titer, dilution of the exact concentration of the output chemically pure substance in water or another solution and dilution of the extracted solution to the required volume. Znayuchi masu (A ) dissolved in chemically pure water and the volume (V) of the dissolved solution, it is easy to calculate the titer (T) of the prepared reagent:

T = a/V (g/ml)

In this way, titrations of such compounds are prepared, which can be easily isolated in a pure form and the composition of which corresponds exactly to the formula and does not change during the conservation process. The direct method of preparing titrations will only stagnate in certain situations. In this way it is not possible to prepare titrated compounds that are highly hygroscopic, easily consume crystallized water, add carbon dioxide, etc.

2. Setting the titer for additional installation speech

This method is used to establish titres of bases on prepared reagents to approximately the required normality and then accurately to the determined concentration.Titeror elsenormalityof the prepared product, titrate it according to its titleinstructive speeches.

A natural speech is called a chemically pure semi-precisely known warehouse that is used to establish the titer of the meaning of another speech.

On the data table for the titration of the mixture, calculate the exact titer or the normality of the prepared substance.

The concentration of a chemically pure mixture is prepared by dividing the calculated volume of water (known in analytical units) and then bringing the volume to a full volume in a still flask. The parts (aliquots) of the mixture prepared in this manner are selected from the still flask with a pipette in the final flask and titrated with their mixture, the titer of which is set. Titration is carried out several times and the average result is taken.

VILICHENYA IN VOLUMETRIC ANALYSIS.

1. Calculation of the normality of the analyzed department for the normality of the worker department

When two speeches interact, the gram equivalent of one speech reacts with the gram equivalent of the other. The divisions of different speeches of the same normality have a place in equal obligations, however, the number of gram-equivalents of the broken speech. However, it is the obligation of such riots to take revenge on the equivalent amount of speech. Therefore, for example, for neutralization 10 ml 1 N. HCI needs to be consumed exactly 10 ml 1N. dissolution of NaOH.The differences of the new normality come into reaction in equal obligations.

Knowing the normality of one of the two reacting factors and their expenses spent on titrating one of the other, it is easy to recognize the unknown normality of the other factor. The normality of the first division is significant in terms of N 2 ta yogo kissed through V 2 . Then, on the basis of what has been said, jealousy can be reduced

V 1 N 1 =V 2 N 2

2. Calculation titration behind a robotic speech.

This is expressed in grams of the mass of the extracted wine, which is contained in one ml of the extract. Calculate the titer as the ratio of the mass of the extracted substance to the volume of the extract (g/ml).

T = m/V

de: m - mass of the divided speech, g; V - zagalny obsyag rozchinu, ml;

T=E*N/1000.(g/ml)

The methods for determining the exact concentration of titrations are called so-calledcorrection factoror elseamendment to.

K = the hanging has actually been taken/the hanging has been secured.

The amendment shows how the number needs to be multiplied by the duty of this duty in order to bring the duty to normality.

Obviously, if the correction for a given category is greater than one, then the normality of that value is greater than the norm that is taken as the standard; If the correction is less than one, then the actual norm is less than the standard normality.

Stock: Z 1.3400G X. year.NaClcooked 200ml Rozchina. Calculate the correction for the reduced concentration of the prepared rosemary exactly 0.1 n.

Decision. U 200ml O,1n. RozchinaNaClmay get tired

58.44 * 0.1 * 200/1000 = 1.1688g

Zvidsi: K = 1.3400 / 1.1688 = 1.146

The correction can be applied to match the titre of the prepared substance to the titre of the singing normality:

K = Titer of prepared rose/ titer of singing normality

In the case of the butt, the titer of the prepared rose is more than 1.340/200= 0.00670g/ml

Titr 0.1 N per unitNaClmore than 0.005844g/ml

Zvidsi K = 0.00670 / 0.005844 = 1.146

Abstract: If the amendment for a given category is greater than one, then the normality of that value is greater than the norm that is taken as the standard; If the correction is less than one, then the normality of one less than the standard is valid.

3. Calculation of the number of speeches, which is indicated by the title of the working unit, expressed in grams is indicated by the speech.

The titer of the working solution in grams is calculated as the number of grams of the working solution, which is equivalent to the amount of speech that can be contained in 1 ml of the working solution. Knowing the titer of the workpiece according to the value of the resin T and the amount of the workbench spent on titration, you can calculate the number of grams (mass) of the resin that is indicated.

butt. Calculate the percentage change Na 2 CO 3 For example, for titration, weigh 0.100 g. vitrified 15.00 ml 0.1 n.HCI.

Decision .

M(Na 2 CO 3 ) =106,00 gr. E(Na 2 CO 3 ) =53,00 gr.

T(HCI/Na 2 CO 3 )= E(Na 2 CO 3 )* N HCI./1000 G/ ml

m(Na 2 CO 3 ) = T(HCI/Na 2 CO 3 )V HCI=0,0053*15,00=0,0795 G.

Vіdsotkovy vmіst Na 2 CO 3 more than 79.5%

4. Calculation of the number of milligram-equivalents of the studied speech.

Having multiplied the normality of the working quantity by the volume, spent on the titration of the traced speech, we subtract the number of milligram equivalents of the graded speech in the titrated part of the traced speech.

List of Wikilists

Alekseev V. N. “Kilkis analysis”

Zolotov Yu. A. “Fundamentals of analytical chemistry”

Kreshkov A. P., Yaroslavtsev A. A. “Course of analytical chemistry. Kilkis analysis"

Piskaryova S. K., Barashkov K. M. “Analytical chemistry”

Shapiro S. A., Gurvich Y. A. "Analytical chemistry"

It’s easy to send your money to the robot to the base. Vikorist the form below

Students, post-graduate students, young people, who have a strong knowledge base in their new job, will be even more grateful to you.

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Ministry of Education and Science of the Russian Federation

Federal state budgetary education for the establishment of high professional education

"Pivdenno-Ural State University"

(National Pre-State University)

Department of "Technology and organization of food"

Preparation of dissolving acids

Vikonala: Sharapova V.M.

Verified by: Sidorenkova L.A.

Chelyabinsk 2014 r.

1. Preparation of acid solutions
2. Rostering conditions when preparing ingredients and the particularities of preparing foodstuffs with different concentrations
2.1 Refreshments under the hour of preparation of ingredients of normal concentration
2.2 Dispersions under the hour of preparation of wines, the concentration of which is expressed in grams per 1 l
2.3 Rozhrakhanki under the hour of preparation of different parts of the song's high concentration

1. Preparation of acid solutions

In analyzes using the neutralization method, the value is 0.1. ta 0.5 n. precisely in the determination of acidic and hydrochloric acids, and in other methods of analysis, for example in oxidation, often use 2 n. Approximate breakdown of these acids.

For easy preparation of precise measurements, manually use fixing agents such as weighed (0.1 g-eq or 0.01 g-eq) chemically pure substances, which are important with an accuracy of up to four to five significant figures, which is required in sealed cursed ampoules. When prepared 1 liter. the price from the fixan will be 0.1 n. or 0.01 star break it up. Small quantities of hydrochloric and sulfuric acids 0.1 N. concentrations can be prepared from fixings. Standard tests prepared from fixants are intended to be used to establish or verify the concentration of other substances. Fixed acids can save time.

To prepare the exact solution from the fixan, wash the ampoule with warm water, write on the label and wipe it well. If you have written the details with farboi, you will see them with gancherka soaked in alcohol. A beaker has a capacity of 1 liter. insert a curse into the glass, and into it - a curse striker, the holy end of which may be straightened up. After this, lightly hit the ampoule with fixan with its thin bottom against the fire striker, or let it fall freely, so that the bottom breaks when hit by the striker. Then, using a glass with a sharpened end, break the thin wall of the embedment at the top of the ampoule and allow the liquid to sit in the ampoule to evaporate. Then carefully rinse the ampoule that is in the bottle with distilled water from the washing bowl, after which remove it from the basin, rinse the tray and remove it from the flask, and add distilled water to the mark in the flask, cap it with a stopper. and mix.

When preparing products from dry fixing agents (for example, from oxalic acid fixing agent), take a dry vial so that instead of an ampoule, you can transfer it into the flask when slightly shaken. After transferring the liquid to the flask, rinse the ampoule and funnel, dissolve the liquid in the water in the flask, and bring the volume to the mark with distilled water.

Great quantities 0.1 star. ta 0.5 n. The contents of hydrochloric and sulfuric acids, as well as similar grades of these acids (2 n. and in) are prepared from concentrated chemically pure acids. Typically, a hydrometer or densimeter indicates the strength of concentrated acid.

For thickness in the pre-test tables, find the acid concentration (substituting chloride of water in hydrochloric acid or monohydrate in acid), expressed in grams per 1 liter. The formulas are based on concentrated acid, which requires the preparation of a given acid of a similar concentration. The analysis is carried out with accuracy to two or three significant figures. The volume of water for preparing acid is determined by the difference in volume of acid and concentrated acid.

Table 1. Alkalinity and concentration of hydrochloric acid (15°C)

Thickness g/cm 3		Thickness g/cm 3

Table.2 Alkalinity and concentration of sulfuric acid components (15°C)

Thickness g/cm 3

Hydrochloric acid is prepared by pouring half the required amount of distilled water into a mixing vessel, then concentrated acid; After mixing the ingredients, add the remaining amount of water to the full volume. Rinse the beaker with part of another portion of water, which was used to measure the acid.

The solution of sulfuric acid is prepared by gradually pouring concentrated acid with constant stirring (to prevent heating) to water poured into a container from a heat-resistant glass. When the quantity of water is low, pour out the beakers for rinsing, with which the acid is added, adding excess moisture after cooling.

Uses for chemical analysis include the determination of solid acids (oxalic, tartaric, etc.). These procedures are prepared for the preparation of chemically pure acid from distilled water.

The weight of the acid is calculated according to the formula. The volume of water for dissolution should be approximately equal to the volume of dissolution (as dissolution is carried out over a peace flask). To dissolve these acids, stagnate the water so as not to remove carbon dioxide.

In the table below, the thickness is found instead of chloride water, HCl in concentrated acid: G k = 315 g/l.

The volume of concentrated hydrochloric acid is:

V k = 36.5N * V / T k = 36.5 * 0.1 * 10000 / 315 = 315 ml.

The amount of water required for preparing wine is:

V H2O = 10000 – 115 = 9885 ml.

Mass of weighed oxalic acid H2C2O4*2H2O:

63.03 N * V / 1000 = 63.03 * 0.1 * 3000 / 1000 = 12.6 rubles.

Establishment of the concentration of working acids can be carried out with sodium carbonate, borax, finely-distilled meadow (titrated or prepared with fixan). When the concentration of hydrochloric or sulfuric acids in sodium carbonate or borax is established, it is determined by the method of titration of residues or (rarely) by pipetting method. When using the hanging titration method, use burettes with a capacity of 50 or 25 ml.

When the acid concentration is set, the indicator value is selected. Titruvannya Vikonyot at the presence of such an izondicator, in the yak -over the bastard, it is in izhtervalvi pH, the vidpovіd qi -ekvyvalenosti for the XIMICHICHICHIA, and the PROTIKAK under the tittruvanny. When a strong acid interacts with a strong base, methyl orange, methyl red, phenolphthalein and others can be used as indicators, in which the barbarization transition occurs at pH = 4:10.

When a strong acid interacts with a weak base or with salts of weak acids and strong bases, indicators of vicorism are those in which the transition of fermentation occurs in an acidic medium, for example, methyl orange. When weak acids interact with strong acids, indicators are formed, in which the transition of fertilization is observed in the meadow middle substance, for example, phenolphthalein. The concentration of acid cannot be determined by titration, since when titrating between a weak acid and a weak base.

When the concentration of hydrochloric or sulfuric acid is set to sodium carbonate in analytical containers, in large bottles, take three or four quantities of anhydrous chemically pure sodium carbonate with an accuracy of up to 0.0002 rub. To set the concentration to 0.1 N. The procedure for titration using a burette with a capacity of 50 ml. . Boxes with excess carbonate are important and, according to the difference in mass, indicate the exact mass of the skin.

Titration of sodium carbonate with acid is carried out with the presence of 1-2 drops of 0.1% methyl orange (titration will end in an acidic solution) until the yellow liquid is changed to orange-yellow. When titrating, use a mixture of distilled water to prepare distilled water, pour it into the same flask as the flask in which the titration is being carried out, add one drop of acid from the burette and a few drops of the indicator as you add it to the titration. , what is titrated .

The volume of distilled water for preparing the titration - “certificate” is due to approximately the same amount of distillation in the flask at the end of the titration.

The normal acid concentration is determined by the titration results:

N = 1000m n/E Na2CO3 V = 1000m n/52.99V

de m n - weight of soda, g;

V - sample of acid (ml), test for titration.

From several traces, take the average concentration value that is avoided.

Approximately 20 ml of acid is allowed for titration.

Masa with soda:

52.99*0.1*20/1000 = 0.1 rub.

butt 4. The addition of sodium carbonate 0.1482 g is titrated with 28.20 ml of hydrochloric acid. Determine the acid concentration.

Normal concentration of hydrochloric acid:

1000*0.1482/52.99*28.2=0.1012 n.

When the concentration of acid is set on sodium carbonate by pipetting method, chemically pure sodium carbonate is first brought to a stable mass by drying in a drying rack and is measured with an accuracy of up to 0.000 2 g, dissolved in distilled water in calibrated ml.

The magnitude of the increase at the installed concentration is 0.1 mag. The amount of acid is approximately 0.5 g (when dissolving, keep approximately 0.1 n. dilution). For titration, pipet 10-25 ml of sodium carbonate solution (to the capacity of the burette) and 1-2 drops of 0.1% methyl orange solution.

The pipetting method often fails when the concentration of ingredients is set using a microburette with a capacity of 10 ml at a cost of 0.02 ml.

The normal concentration of acid when it is established by pipetting with sodium carbonate is calculated using the formula:

N = 1000m n V 1 / 52.99V to V 2,

de m n - weight of sodium carbonate, g;

V 1 - volume of carbonate, taken for titration, ml;

V up to - a peaceful flask in which the suspension of carbonate was dissolved;

V 2 - analyzed the acid, tested for titration.

Butt 5. Calculate the concentration of sulfuric acid, so that 0.5122 g of sodium carbonate was added to a 100.00 ml glass flask and 14.70 was spent on titration of 15.00 ml of sodium carbonate. ml dilution of acid (with vikoristan burettes.

The normal concentration of sulfuric acid is:

1000*0.5122*15/52.99*100*14.7 = 0.09860 n.

When the concentration of sulfuric or hydrochloric acids is set after sodium tetraborate (borax) Start the vikorist method of titrating navazhok. The crystalline hydrate of borax Na 2 B 4 O 7 *10H 2 O must be chemically pure and recrystallized before adjusting the acid concentration to a new level. For recrystallization, 50 g of borax are dissolved in 275 ml of water at 50-60°C; Then filter and cool to 25-30°C. Energetically stirring the destruction, call for crystallization. The crystals are filtered on a Buchner filter, separated again and recrystallized. After filtering, the crystals were dried between sheets of filter paper at a temperature of 20°C and aqueous moisture of 70%; Drying is carried out on the air or in a desiccator over saturated sodium chloride. Dried crystals are not guilty of sticking to the curse stick.

For Titrvannya, the Box of Boxing 3-4 Posyshuvannya Bury is accurate up to 0.0002 g I to transfer the Kolbi for Titrvannya, Rosichychi Kozhnu Vyshuvannya in 40-50 ml of heat under the yenergye zbovovanni. After transferring the skin from the beaker to the flask, it is called a beaker. According to the difference in weight, the size of the skin is determined. The size of the surrounding storm to establish a concentration of 0.1 N. The amount of acid in a frozen burette containing 50 ml is about 0.5 g.

Titration of stains with acid is carried out in the presence of 1-2 drops of 0.1% methyl red to the change of yellow barley in orange-red or in the presence of a mixed indicator, which consists of methyl red and methylene blue .

The normal concentration of acid is determined by the following formula:

N = 1000m n / 190.69V,

de m n – weight of the storm, g;

V - acid analysis, titration, ml.

For titration, add 15 ml of diluted acid.

Masa of the storm:

190.69*0.1*15/1000 = 0.3 rub.

Butt 7. Find the concentration of hydrochloric acid, if 24.38 ml of hydrochloric acid was consumed to titrate a sample of 0.4952 g.

1000 * 0,4952 / 190,624,38 = 0,1068

Establishing the concentration of acid behind the solution of sodium hydroxide Or the potassium hydroxide is titrated with rosemary acid in the presence of 1-2 drops of 0.1% methyl orange. However, this method of determining the acid concentration is less accurate and has lower guidance. Just make sure to check the concentration of acids during the period of control checks. As a weekend farmer, he often rinses himself with rosemary meadows prepared from fixan.

The normal concentration of acid N 2 is determined by the following formula:

N 2 = N 1 V 1 / V 2

de N 1 – normal concentration in the meadow;

V 1 - volume of analysis, samples for titration;

V 2 - analysis of the acid, using for titration (the average value of the titration results, which converges).

Butt 8. Calculate the concentration of sulfuric acid by titrating 25.00 ml with 0.1000 N. 25.43 ml of sodium hydroxide was used to dissolve sulfuric acid.

Acid concentration:

0.1*25/25.43 = 0.09828 n.

2. Rostering conditions when preparing ingredients and the particularities of preparing foodstuffs with different concentrations

rozchin acid concentration beaker

The accuracy of the measurements when preparing the items depends on what kind of order is being prepared: approximate or accurate. When disclosing approximate quantities, atomic and molecular masses are rounded to three digits. So, for example, the atomic weight of chlorine is taken to be equal to 35.5 displacement of 35.453, the atomic weight of water - 1.0 displacement of 1.00797, etc. The rounding is carried out on the larger side.

When preparing standard payments, calculations are carried out with an accuracy of up to five digits. Atomic masses of elements are taken with such precision. In case of breakdowns, they use five-digit and several-digit logarithms. Discuss the concentration of which is then established by titration, preparation, and approximation.

Dilutions can be prepared for the preparation of solid substances, or dilute more concentrated substances.

2.1 Refreshments under the hour of preparation of ingredients of normal concentration

The importance of speech (g) for preparing the standard of singing normality is to be covered by the following formula:

m n = ENV/1000,

where E is the chemical equivalent of the word that is being broken down;

N - required normality, g-eq/l;

V – volume of volume, ml.

The importance of speech is to be dismantled at the peaceful flask. Dilutions of approximation can be prepared by dividing the liquid in the volume of the distributor, so that the same volume is used. This volume can be measured by a cylinder or beaker.

When preparing to weigh the crystalline hydrate, then in the scale of calculations, to determine the weight, introduce the value of the chemical equivalent of the crystalline hydrate.

When preparing the rosemary with a normal concentration, dilute the concentrated amount of the concentrated amount (ml) according to the formula:

V to = ENV/T to,

de T to - concentration of concentrated alcohol, g/l, or:

de N to - normality of concentrated distribution, or:

V to = ENV/10 p to d to,

de p to - percentage concentration of the concentrated product;

d to - concentrated thickness, g/cm 3 .

Concentrated ingredients are diluted in still flasks. When preparing precision doses (for example, standard doses larger than a concentrated standard dose), mix the concentrated doses with pipettes or add them from burettes. When preparing approximate dilutions, you can work by mixing the concentrated solution with the volume of water, so that the traditional differences between the volumes of dilute and concentrated solution:

2.2 Dispersions under the hour of preparation of wines, the concentration of which is expressed in grams per 1 l

The value of weight gain (g) for such divisions is calculated using the formula:

de T – concentration of alcohol, g/l;

V – volume of volume, ml.

Disintegrated speech should be carried out at the peaceful flask with the volume being adjusted after disintegration to the mark. Approximately, you can prepare the mixture by hanging it in a volume of water, which will equal the previous volume.

When the mixture is prepared with the addition of crystal hydrate, and the concentration of the solution is expressed by dividing it into anhydrous solution, the concentration of crystal hydrate is calculated using the formula:

m n =TVM k /1000M,

where M k is the molecular weight of the crystal hydrate;

When preparing rosemary by diluting more concentrated volumes of concentrated rosemary, the amount of concentrated wine is calculated using the formula:

where T k is the concentration of the concentrated product, g/l, or:

V up to =100VT/1000p k d k ,

where p k is the percentage concentration of the concentrated product;

d k - thickness of concentrated powder, g/cm 3;

V to =VT/EN k,

de N k – normal concentration of concentrated rosemary; E – chemical equivalent of speech.

The ingredients are prepared in the same way as when preparing the ingredients of the normal concentration, the way is to dilute more concentrated ingredients.

For close distributions associated with the preparation of divisions by diluting greater concentrations, one can use the rule of dilution (the “rule of cross”), in order to determine what is involved in divisions that are mixed, in return to the proportional differences the concentration of the mixed substances and the contents removed during mixing. Shown in diagrams:

de N 1, T 1, N 3, T 3 - concentrations of substances that are mixed;

N 2 T 2 - concentration of powder removed during mixing;

V 1, V 3 - obsyagy rozchiniv, sho zmіsuyu.

If you prepare dilutions of a concentrated solution with water, then N 3 = 0 or T 3 = 0. For example, for preparing a solution, the concentration of T 2 = 50 g/l from the concentration of T 1 = 100 g/l and T 3 = 20 g/l it is necessary to mix the volume V 1 = 50 - 20 = 30 ml for a concentration of 100 g/l and V 3 = 100 - 50 = 50 ml for a concentration of 20 g/l:

2.3 Rozhrakhanki under the hour of preparation of different parts of the song's high concentration

Masu navishuvannya (d) to be protected by the following formula:

where p is the concentration of concentration;

Q – masa rozchinu, city.

For tasks with a volume of V, the mass of the cost is designated:

de d - thickness, g/cm 3 (can be found in pre-test tables).

The weight of the weight at a given volume will be insured:

Masa water for breaking up hanging means:

The remaining mass of water is approximately equal in size to its volume, so the water should be measured with a still cylinder.

If the solution is to prepare the crystalline hydrate of the resin, and the concentration of the solution is in hundreds of anhydrous resin, then the mass of the crystal hydrate should be prepared according to the formula:

m n = pQM k /100M,

de M k - molecular weight of the crystal hydrate;

M is the molecular weight of anhydrous rheuceum.

The preparation of dilute dilutions of greater concentrations is carried out manually by mixing the necessary water and water, at which volume of the concentrated dose is calculated using the formula:

V = pdV/p k d k ,

de d k - The strength of the concentrated powder.

The differences in the percentage concentration are prepared as approximations, and therefore the weighting of speeches to an accuracy of two or three significant figures is important on technical grounds, and for the purpose of understanding the obligations, use beakers or peaceful cylinders drams

If the differences are determined by the mixing of two other categories, one of which has a greater concentration, and the other - a smaller one, then the mass of the output categories can be calculated using the dilution rule (the “cross rule”), which is the percentage for the categories and concentrations to compare: masses of disorders that mix , inversely proportional to the differences in the percentage concentrations of the mixtures and the resulting crimes. This rule is illustrated by a diagram:

For example, to remove the difference in concentration p 2 = 10% of the concentration difference p 1 = 20% and p 3 = 5%, you need to mix a number of output values: m 1 = 10-5 = 5 g of 20% difference and m 3 = 20 - 10 = 10g of 5% dose. Knowing the density of differences, you can easily determine the volumes necessary for mixing.

Principles of preparation and distribution in volumetric analysis. Preparation of titrations of sulfuric and hydrochloric acids

The requirement is to be corrected with accuracy to the fourth tenth decimal place, and molecular weights are taken with the accuracy indicated in the subdivision tables. The volume of concentrated acid is adjusted to the nearest tenth place.

It’s easy to send your money to the robot to the base. Vikorist the form below

Ministry of Education and Science of the Russian Federation

Federal state budgetary education for the establishment of high professional education

"Pivdenno-Ural State University"

(National Pre-State University)

Department of "Technology and organization of food"

Preparation of dissolving acids

Vikonala: Sharapova V.M.

Verified by: Sidorenkova L.A.

Chelyabinsk 2014 r.

1. Preparation of acid solutions

2. Rostering conditions when preparing ingredients and the particularities of preparing foodstuffs with different concentrations

2.1 Refreshments under the hour of preparation of ingredients of normal concentration

2.2 Dispersions under the hour of preparation of wines, the concentration of which is expressed in grams per 1 l

2.3 Rozhrakhanki under the hour of preparation of different parts of the song's high concentration

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