We prepare electrolyte for batteries at home ourselves. Calculations for diluting and concentrating solutions Sulfuric acid is dissolved in hot water

For safety and ease of use, it is recommended to buy the acid as diluted as possible, but sometimes you have to dilute it even more at home. Don't forget to wear protective equipment for your body and face, as concentrated acids cause severe chemical burns. To calculate the required amount of acid and water, you will need to know the molarity (M) of the acid and the molarity of the solution you need to obtain.

Steps

How to calculate the formula

Explore what you already have. Look for the acid concentration designation on the packaging or in the task description. This value is usually indicated as molarity, or molar concentration (M for short). For example, 6M acid contains 6 moles of acid molecules per liter. Let's call this initial concentration C 1.

• The formula will also use the value V 1. This is the volume of acid we will add to the water. We likely won't need the entire bottle of acid, although we don't know the exact amount yet.

1. Decide what the result should be. The required concentration and volume of acid are usually indicated in the text of the chemistry problem. For example, we need to dilute the acid to 2M, and we will need 0.5 liters of water. Let us denote the required concentration as C 2, and the required volume is as V 2.

   • If you are given other units, first convert them to molarity units (moles per liter) and liters.
   • If you don't know what concentration or volume of acid is needed, ask a teacher or someone knowledgeable about chemistry.

2. Write a formula to calculate the concentration. Each time you dilute an acid, you will use the following formula: C 1 V 1 = C 2 V 2. This means that the original concentration of a solution multiplied by its volume equals the concentration of the diluted solution multiplied by its volume. We know that this is true because the concentration times the volume equals the total amount of acid, and the total amount of acid will remain the same.

   • Using the data from the example, we write this formula as (6M)(V 1)=(2M)(0.5L).

3. Solve equation V 1. The V 1 value will tell us how much concentrated acid we need to get the desired concentration and volume. Let's rewrite the formula as V 1 =(C 2 V 2)/(C 1), then substitute the known numbers.

   • In our example, we get V 1 =((2M)(0.5L))/(6M). This equals approximately 167 milliliters.

4. Calculate the required amount of water. Knowing V 1, that is, the available volume of acid, and V 2, that is, the amount of solution that you will get, you can easily calculate how much water you will need. V 2 - V 1 = required volume of water.

   • In our case, we want to get 0.167 liters of acid per 0.5 liter of water. We need 0.5 liters - 0.167 liters = 0.333 liters, that is, 333 milliliters.

5. Wear safety glasses, gloves and a gown. You will need special glasses that will cover the sides of your eyes as well. To avoid burning your skin or burning through your clothing, wear gloves and a robe or apron.

   Work in a well-ventilated area. If possible, work under a switched-on hood - this will prevent acid vapors from harming you and surrounding objects. If you don't have a hood, open all windows and doors or turn on a fan.

6. Find out where the source of running water is. If the acid gets into your eyes or skin, you will need to rinse the affected area under cool running water for 15-20 minutes. Don't start working until you know where the nearest sink is.

   • When rinsing your eyes, keep them open. Look up, down, to the sides so that your eyes are washed from all sides.

7. Know what to do if you spill acid. You can buy a special kit for collecting spilled acid, which will include everything you need, or purchase neutralizers and absorbents separately. The process described below is applicable to hydrochloric, sulfuric, nitric and phosphoric acids. Other acids may require different handling.

   • Ventilate the room by opening windows and doors and turning on the hood and fan.
   • Apply A little sodium carbonate (soda), sodium bicarbonate, or calcium carbonate onto the outer edges of the puddle, ensuring that the acid does not splash.
   • Gradually pour the entire puddle towards the center until you cover it entirely with the neutralizing substance.
   • Mix thoroughly with a plastic stick. Check the pH value of the puddle with litmus paper. Add more neutralizing agent if the reading is greater than 6-8, then rinse the area with plenty of water.

How to dilute acid

1. Cool the water with luda. This should only be done if you will be working with high concentration acids, for example, 18M sulfuric acid or 12M hydrochloric acid. Pour water into a container and place the container on ice for at least 20 minutes.

   • Most often, water at room temperature is sufficient.

2. Pour distilled water into a large flask. For applications requiring extreme precision (such as titrimetric analysis), use a volumetric flask. For all other purposes, a regular conical flask will do. The container must fit the entire required volume of liquid, and there must also be room so that the liquid does not spill.

   • If the capacity of the container is known, there is no need to accurately measure the amount of water.

How to mix two liquid substances? For example, some acid and water? It would seem that this problem is from the series “twice two is four.” What could be simpler: drain the two liquids together in some suitable container, and that’s it! Or pour one liquid into a container that already contains another. Alas, this is the same simplicity that, according to an apt popular expression, is worse than theft. Because things can end extremely sadly!

Instructions

There are two containers, one of them contains concentrated sulfuric acid, the other contains water. How to mix them correctly? Should we pour acid into water or, conversely, water into acid? The price of a wrong decision in theory can be a low score, but in practice - at best, a severe burn.

Why? But because concentrated sulfuric acid, firstly, is much denser than water, and secondly, it is extremely hygroscopic. In other words, it actively absorbs water. Thirdly, this absorption is accompanied by the release of a large amount of heat.

If water is poured into a container with concentrated sulfuric acid, the first portions of water will “spread” over the surface of the acid (since water is much less dense), and the acid will begin to greedily absorb it, releasing heat. And there will be so much heat that the water will literally “boil” and splashes will fly in all directions. Naturally, without avoiding the hapless experimenter. Getting burned with “clean” boiling water is not very pleasant, but considering that the water spray will probably still contain acid. The prospect is becoming completely gloomy!

That is why many generations of chemistry teachers forced their students to literally memorize the rule: “First water, then acid! Otherwise, big trouble will happen!” Concentrated sulfuric acid should be added to water in small portions with stirring. Then the unpleasant situation described above will not happen.

A reasonable question: it’s clear with sulfuric acid, but what about other acids? How to properly mix them with water? In what order? It is necessary to know the density of the acid. If it is denser than water, for example, concentrated nitrogen, it should be added to water, just like sulfur, observing the above conditions (little by little, with stirring). Well, if the density of the acid differs very slightly from the density of water, as is the case with acetic acid, it makes no difference.

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In some cases, the acid, after mixing in a small tank, enters pipes irrigated with water from outside, where it is simultaneously cooled and further mixed.

When mixing concentrated sulfuric acid with water or more dilute sulfuric acid, it is necessary to calculate the amount of acids mixed. Calculations are carried out according to the so-called rule of the cross. Below are some examples of such calculations.

1. Determine the amount of 100% sulfuric acid and water that must be mixed to obtain 45% II2SO|.

On the left indicate the concentration of a more concentrated acid (in this case 100%), and on the right - a more dilute one (in this case 0% water). Below, between them, indicate the specified concentration (45%). Crossing lines are drawn through the number indicating this concentration, and the corresponding difference in numbers is indicated at their ends:

The numbers obtained using acids of initial concentrations show how many parts by mass of the acid of each of the indicated concentrations must be mixed to obtain an acid of a given concentration. In our example, to prepare 45% acid, you should mix 45 wt. including 100% acid n 55 wt. hours of water.

The same problem can be solved based on the overall balance of II2SO4 (or S03) in sulfuric acid:

0,45.

The numerator on the left side of the equation corresponds to the H2S04 content (in kg) in I kg of 100% sulfuric acid, the denominator corresponds to the total amount of a given solution (in kg). The right side of the equation corresponds to the concentration of sulfuric acid in fractions of unity. Solving the equation, we get x-1.221 kg. This means that 1.221 kg of water must be added to 1 kg of 100% sulfuric acid, resulting in 45% acid.

2. Determine the amount of 20% oleum that should be mixed with 10% nonsulfuric acid to obtain a 98% acid.

The problem is also solved using the cross rule, however, the concentration of oleum in this example must be expressed in % H2SO4 using equations (9) and (8):

A --= 81.63 + 0.1837-20 --= 85.304;

B 1.225-85.304 - 104.5.

According to the rule of the cross

Therefore, to obtain 98% sulfuric acid, it is necessary to mix 88 wt. including 20% ​​oleum and 6.5 wt. including 10% sulfuric acid.

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1. Are the following statements true about the rules of safe work in the school laboratory?

A. When carrying out experiments with con-cen-tri-ro-van-ny-mi dis-tvor-mi acids and alkali non-ob-ho-di -we always have to re-zi-new gloves.

B. Experiments with le-tu-chi-mi, poisonous substances are carried out only under traction.

1) only A is true

2) only B is true

3) both statements are true

2. Which of the gases that are present in the at-mo-sphere in the re-zul-ta-te de-i-tel-no-sti of a person is the most more tok-si-chen?

1) CO2 2) NO23) CH4 4) H2

3. What mixture can be filtered?

1) sa-ha-ra and water

2) sand and water

3) water and gasoline

4) sand and sa-ha-ra

4. Are the assumptions about safe handling of chemical substances correct?

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

5. Are the following statements true about the rules of work in the school lab?

A. On any container in which substances are stored, there should be these boxes with names or shapes -la-mi substances.

B. Experiments with gases and food substances should not be carried out using glasses of your own or la-bo -ra-tor-nykh.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

6. Are the following conclusions about the rules of safe work in the hi-mi-che-la-bo-ra-to-ria correct?

B. Sulfuric acid should be dissolved in hot water.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

7. Are the following conclusions about pure substances and mixtures and ways of dividing them correct?

A. Pure substances have a constant composition.

B. A mixture of boiled salt and river sand can be diluted by adding water and then fil-tro-va-niya and you-pa-ri-va-niya.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

8. Are the following statements about car exhaust gases true?

A. The most harmful component of exhaust gases is CO2, since it is a vapor gas.

B. Nitrogen oxides are formed through the interaction of a car with nitrogen air -Ha.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

9. Are the following conclusions about the rules of safe work in the hi-mi-che-la-bo-ra-to-ria and with pre-pa-ra-ta-mi would-how chemistry?

A. In la-bo-ra-to-rii, the sourness in the solution is determined by the taste.

B. When working with pre-pa-ra-ta-mi of chemistry, containing alkali, not-about-ho-di-mo is-used -re-new gloves.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

10. Are the assumptions about the ability to create mixtures correct?

A. A mixture of ethanol and water can be diluted using a funnel.

B. The effect of a mag-ni-tom on a mixture of iron and alu-mi-ni-e opi-locks is in a physical way -de-le-tion of substances.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

11. Are the following conclusions about the interaction with gases in the process of laboratory experiments correct?

A. Before you set fire to the water, you shouldn’t check it for cleanliness.

B. Chlorine, which is obtained from salt, cannot be determined by its smell.

1) Only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

12. Are the following conclusions about the rules of safe work in La-bo-ra-to-ria correct?

A. When heating the sample with a solution of boiled salt, do not use protective glasses.

B. When transferring the liquid into the sample, you can close the hole of the sample with your hand.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

13. Are the following conclusions about the process of filtration and the use of chemical re-acs correct? -tsiy hu-lo-ve-kom?

A. To speed up the filtering process, the beveled end of the funnel should be pressed against the wall. -th hundred-ka-na.

B. At the core of the melting of iron and steel there are oxidation reactions.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

14. Sodium chloride can be isolated from its aqueous solution using

1) filtering

2) you-pa-ri-va-niya

3) magician

4) from-sta-i-va-niya

15. Are the assumptions about the ability to create mixtures correct?

A. Sea water can be purified from salts dissolved in it using filtration.

B. Per-re-gon-ka is revealed in a hi-mi-che-like way of dividing mixtures.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

16. Are the judgments about the rules of using and storing pre-pa-ra-tov household chemicals correct?

A. Aero-zo-li, is-used as a means to fight against whatever is on us, safe for children and animals.

B. Products and detergents should be stored in places accessible to children.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

17. Are the judgments about safe handling of chemical substances correct?

A. The broken mercury thermometer and the mercury that leaked out of it should be thrown into the trash can.

B. Paint, containing lead ions, should not be used to cover children's toys and su-doo.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

18. Are the following conclusions about the rules of safe work in the hi-mi-che-la-bo-ra-to-ria correct?

A. Methane forms explosive mixtures with air.

B. Dissolve sulfuric acid by adding water to it.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

19. Are the following statements about pure substances and mixtures true?

A. Natural gas is a pure substance.

B. Diamond is a mixture of substances.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

20. Are the following statements about water true?

A. Sea water has a greater density than river water, since it contains a significantly larger amount of water. content of dissolved salts.

B. Water is filled with memory, so water can be used for recording information.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

21. Are the following conclusions about the rules of storing and receiving vitamins correct?

A. Vi-ta-min C can be consumed in an unlimited quantity.

B. It is possible to store and receive vi-ta-mi-nas in a non-limited period of time.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

22. Are the following statements about carbon dioxide gas true?

A. The amount of carbon gas in the at-mo-sphere is growing bla-go-da-rya-tel-no- sti che-lo-ve-ka.

B. Carbon dioxide is the most harmful component of exhaust gases.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

23. What elements in drinking water are most toxic for humans?

1) sodium and calcium chlorides

2) sulfate calcium and magnesium

3) salts of lead and mercury

4) created-my car-bo-na-you

24. Are the following statements true about the rules of work in the school lab?

A. Substances found in la-bo-ra-to-ria are prohibited from tasting, even if they in everyday life they are consumed in food (for example, sodium chloride).

B. When acid appears on the skin, the affected area should be washed with a large amount of alkali solution.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

25. Are the following statements true about the rules of safe work in the school lab?

A. To extinguish the flame of alcohol, it should be blown out.

B. When heating the sample with the solution, it should be kept strictly vertical.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

26. Are the following statements true about the rules of work in the school lab?

A. All experiments carried out in la-bo-ra-to-ria must be recorded in the la-bo-ra-tor journal.

B. When heating liquid and solid substances in test tubes and flasks, you cannot direct them towards yourself and others .

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

27. Are the following conclusions about the rules of storing vi-ta-mins and pre-knowing my means correct? ?

A. Storing vi-ta-mi-novs does not require strict adherence to the rules specified in the instructions.

B. To remove grease stains from the surface of the surface, use my products properties that have an alkaline environment.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

28. Are the judgments about safe handling of chemical substances correct?

A. The broken mercury thermometer and the mercury that leaked out of it should be thrown into the trash can.

B. Kras-ka-mi, with-k-hold-mi-containing lead, do not re-co-men-du-s-cover children's games- Rush-ki and po-su-doo.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

29. Are the following conclusions about the rules of safe work in the hi-mi-che-la-bo-ra-to-ria correct?

A. In la-bo-ra-to-ria you can’t be familiar with the smell of substances.

B. Water can be boiled in any glass sous-de-like.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

30. Are the judgments about safe handling of chemical substances correct?

A. The broken mercury thermometer and the mercury that leaked out of it should be thrown into the trash can.

B. Kras-ka-mi, with-k-hold-mi-containing lead, do not re-co-men-du-s-cover children's games- Rush-ki and po-su-doo.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

31. Are the following statements about ozone true?

A. Ozone in the stra-t-sphere absorbs part of the ul-tra-fi-o-le-to-of-radiation, protecting from it from -lu-che-nii living or-ga-niz-we.

B. Ozone is a completely harmless gas, which is why it is preferred to use it instead of chlorine for water purification.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

32. Are the judgments about environmental safety true?

A. It is not recommended to eat fruits and vegetables grown from iron ore. roads and highways.

B. Vegetable plants grown with the use of everyday mineral amenities are not - pose a danger to the or-ga-niz-ma of a person.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

33. Are the assumptions about the ability to create mixtures correct?

A. You-pa-ri-va-nie from-to-fi-zi-che-skim sp-so-bam di-de-le-niya mixtures.

B. Dividing the mixture of water and eta may be possible through filtering.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

34. Are the following conclusions about the rules of safe work in the hi-mi-che-la-bo-ra-to-ria and storing substances in everyday life?

A. When the solution dissolves sour on the skin, it should be washed with water and dis-solved with the solution. howl of soda.

B. An easy-to-re-flame liquid, for example, ace-tone, can only be stored ko in ho-lo-dil-ni-ke.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

35. Are the following conclusions about the ways of dividing mixtures correct?

A. To separate a mixture of river sand and iron filings, you can use magnet.

B. To remove sediment from the solution, you can use filter paper.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

36. Are the following statements about water true?

A. Water-containing water contains a mixture of soluble salts - sulphate and hydro-car-bo-na-tov.

B. Water has a memory, which is why it has mechanical influences, for example, sound sounds. ba-nia, its properties change.

1) only A is true

2) only B is true

3) both statements are true

4) both statements are incorrect

37. Are the following conclusions about the rules of safe work in the hi-mi-che-la-bo-ra-to-ria correct?

A. You can heat water in a men-zur-ka.

B. Burning sodium can be extinguished with water.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

38. Are the following conclusions about the ways of co-breathing gases in la-bo-ra-to-ria correct?

A. Carbon-acidic gas can be collected in a vessel by removing the air.

B. Acid can be collected in a vessel using both the removal of air and the removal of water.

1) Only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

39. Are the following conclusions about the ways of obtaining coal-le-acid gas in La-bo-ra-to-ria correct?

A. Coal-le-acidic gas in la-bo-ra-to-rii is dissolved in car-bo-na-that calcium when heated -va-nii.

B. For laboratory experiments, carbon-acidic gas is obtained by heating car-bo-na-ta am-mo-niya .

1) Only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

40. Are the judgments about the environmental safety of chemical production correct?

A. You throw away sulfuric gas, which is formed in the process of obtaining sulfuric acid , have a positive influence on the health of man, the plant and animal world.

B. The processing of lead ores does not pose a threat to the environment and human health. lo-ve-ka.

1) only A is true

2) only B is true

3) both judgments are true

4) both judgments are incorrect

The percentage concentration of a solution expresses the ratio of the mass of the solute to the mass of the solution as a whole. If we dilute a solution by adding a solvent to it, the mass of the solute will remain unchanged, but the mass of the solution will increase. The ratio of these masses (concentration of the solution) will decrease by as many times as the mass of the solution increases. If we begin to concentrate the solution by evaporating the solvent, the mass of the solution will decrease, but the mass of the solute will remain unchanged. The mass ratio (concentration of the solution) will increase as many times as the mass of the solution decreases. It follows that the mass of the solution and the percentage concentration are inversely proportional to each other, which can be expressed in mathematical form as follows: l. This pattern underlies calculations when diluting and concentrating solutions. Example 1. There is a 90% solution. How much of it should be taken to prepare 500 kg of a 20 percent solution? Solution. According to the relationship between the mass and the percentage concentration of the solution. Hence, it is necessary to take 111 kg of a 90% solution and add enough solvent to it so that the mass of the solution becomes equal to 500 kg. Example 2. There is a 15% solution. To what mass should 8.50 tons of this solution be evaporated to obtain a 60% solution? Solution. If the quantities of solutions are given in volumetric units, they must be transferred to masses. In the future, calculations should be carried out according to the method outlined above. Example 3. There is a 40% solution of sodium hydroxide with a density of 1.43 kg/l. What volume of this solution must be taken to prepare 10 liters of a 15% solution with a density of 1.16 kg/l? Wound" We calculate the mass of a 15% solution: kg n the mass of a 40% solution: Determine the volume of a 40% solution: Example 4. There is 1 liter of a 50% solution of sulfuric acid with a density of 1.399 kg/l. To what volume must this solution be diluted to obtain an 8% solution with a density of 1.055 kg/l? Solution. Find the mass of the 50% solution: kg and the mass of the 8% solution: Calculate the volume of the 8% solution: V - - 8.288 -. = 8 l 288 ml Example 5. 1 l of a 50% nitric acid solution, the density of which is 1.310 g/lm, was diluted with 690 ml of water. Determine the concentration of the resulting solution *. Solution. We find the mass of a 50% solution: your = g and the mass of the dilute solution: We calculate the concentration of the dilute solution: 1 Examples No. 5,6,7 are taken from the book Ya L. Goldfarb, Yu. V. Kho-lakova “Collection of problems and exercises in chemistry.” M., “Enlightenment”, 1968 Example c. There is a 93.6% acid solution with a density of 1.830 g/ml. How much of this solution is required to prepare 1,000 liters of a 20% solution with a density of 1,140 g/ml, and how much water is required for this? Solution. We determine the mass of a 20 percent solution and the mass of a 93.6 percent solution required to prepare a 20 percent solution: We calculate the mass of water required to prepare a dilute solution: We find the volume of a 93.6 percent solution: Example 7. How many milliliters of sulfuric acid with a density of 1 .84 g/ml is required to prepare 1,000 liters of battery acid with a density of 1.18 g/ml) The percentage concentration of the solution and its density are in a certain relationship, recorded in special reference tables. Using them, you can determine the concentration of the solution by its density. According to these tables, sulfuric acid with a density of 1.84 g/ml is 98.72 percent, and with a density of 1.18 g/ml - 24.76-