How to properly dilute acid with water. Calculations for diluting and concentrating solutions
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
- 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.
-
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.
-
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).
-
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.
-
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.
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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.
-
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 work 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.
-
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.
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.
How to dilute acid
-
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.
-
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.
1. Are the following statements true about the rules of safe work in the school laboratory?
And -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 judgments 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 hot-ryu-chi-mi and edible substances are not-about-ho-di-mo carried out in glasses - 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 with the help of 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 test 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 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 with the help of filtering.
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 assumptions 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.
1) only A is true
2) only B is true
3) both judgments are true
4) both judgments are incorrect
30. Are the assumptions 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 strat-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 effects, 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-ke.
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-riy true?
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-acid gas is obtained by heating car-bo-na-ta am-mo-niy .
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 eco-friendly 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-
Currently, the choice of rechargeable batteries is huge - on sale you can find ready-to-use power sources, as well as dry-charged batteries that require preparing the electrolyte and filling it before use. Many people often carry out further battery maintenance at service centers. For various reasons, it may be necessary to prepare the solution yourself. For this event to be successful, you should know how to make electrolyte at home.
Electrolyte is an electrically conductive solution containing distilled water and sulfuric acid, caustic potassium or sodium, depending on the type of power source.
Concentration of sulfuric acid in the battery
This acidity indicator directly depends on the required density of the electrolyte. Initially, the average concentration of this solution in a car battery is about 40%, depending on the temperature and climate in which the power source is used. During operation, the acid concentration drops to 10–20%, which affects the performance of the battery.
At the same time, it is worth understanding that the battery’s sulfur component is the purest liquid, which is 93% composed directly of acid, the remaining 7% being impurities. In Russia, the production of this chemical is strictly regulated - products must comply with GOST requirements.
Differences in electrolytes for different types of batteries
Despite the fact that the principle of operation of the solution is the same for different power sources, you should be aware of some differences in the composition. Depending on the composition, it is customary to distinguish alkaline and acidic electrolytes.
Alkaline batteries
This type of power source is characterized by the presence of nickel hydroxide, barium oxide and graphite. The electrolyte in this type of battery is a 20% solution of caustic potassium. Traditionally, the additive of lithium monohydrate is used, which allows to extend the life of the battery.
Alkaline power sources are characterized by the absence of interaction of the potassium solution with substances formed during battery operation, which helps to minimize consumption.
Acid batteries
This type of power supply is one of the most traditional, which is why the solution in them is familiar to many - a mixture of distilled water and sulfur solution. Electrolyte concentrate for lead-acid batteries is inexpensive and characterized by the ability to conduct large currents. The density of the liquid must correspond to climatic conditions.
Other types of batteries: is it possible to prepare electrolyte for them yourself?
Separately, I would like to draw attention to modern lead-acid power supplies - gel and AGM. They can also be filled with a personally prepared solution, which is in a specific form - in the form of a gel or inside separators. To refill gel batteries, you will need another chemical component - silica gel, which will thicken the acid solution.
Nickel-cadmium and iron-nickel batteries
Unlike lead power sources, cadmium- and iron-nickel ones are filled with an alkaline solution, which is a mixture of distilled water and caustic potassium or sodium. Lithium hydroxide, which is part of this solution for certain temperature conditions, allows you to increase the service life of the battery.
Table 2. Composition and density of electrolyte for cadmium- and iron-nickel batteries.
How to properly prepare electrolyte at home: safety precautions
Preparing a solution involves working with acids and alkalis, so taking precautions is necessary for the most experienced people. Before you begin, prepare your protective equipment:
- latex gloves
- chemical-resistant clothing and apron;
- protective glasses;
- ammonia, soda ash or boric solution to neutralize acid and alkali.
Equipment
To prepare battery electrolyte, in addition to the power source itself, you will need the following items:
- container and stick, resistant to acids and alkalis;
- distilled water;
- instruments for measuring the level, density and temperature of the solution;
- battery sulfur liquid - for acid batteries, solid or liquid alkalis, lithium - for the corresponding types of batteries, silica gel - for gel batteries.
Process sequence: making an electrolyte for a lead-acid power source
Before starting work, read the information given in Table 3. It will allow you to select the required volume of liquids. The batteries contain from 2.6 to 3.7 liters of acid solution. We recommend diluting approximately 4 liters of electrolyte.
Table 3. Proportions of water and sulfuric acid.
- Pour the required volume of water into a container that is resistant to caustic substances.
- The water should be diluted with acid gradually.
- At the end of the infusion process, measure the density of the resulting electrolyte using a hydrometer.
- Let the composition sit for about 12 hours.
Table 4. Electrolyte density for different climates.
The concentration of the acid solution must be related to the minimum temperature at which the battery is operated. If the liquid is too concentrated, it must be diluted with distilled water.
Watch the video on how to measure the density of an electrolyte.
Attention! You cannot pour water into acid! As a result of this chemical reaction, the composition may boil, which will lead to its splashing and the possibility of acid burns!
Please note that heat is generated during mixing of the components. The cooled solution should be poured into the prepared battery.
Method for diluting electrolyte for an alkaline power source
The density and amount of electrolyte in such batteries is indicated in the operating instructions for the power source or on the manufacturer’s website.
- Pour distilled water into the bowl.
- Add lye.
- Mix the solution, seal it tightly and let it brew for 6 hours.
- After the time has passed, drain the resulting light solution - the electrolyte is ready.
When sediment appears, stir it. If it remains at the end of settling, drain the electrolyte so that the sediment does not get into the battery - this will lead to a decrease in its service life.
Attention! During work, the temperature of the alkaline solution should not exceed 25 degrees Celsius. If the liquid becomes excessively hot, cool it.
After bringing the solution to room temperature and pouring it into the battery, the power source must be fully charged with a current equal to 10% of the battery capacity (60Ah - 6A).
As you can see, preparing an electrolyte solution is not such a difficult matter. The main thing is to clearly determine the required amount of ingredients and remember about safety. Have you tried diluting electrolyte with your own hands? Share your experience with our readers in the comments.
In factory conditions, it is often necessary to dilute concentrated sulfuric acid with water or increase the concentration of diluted acid by adding concentrated acid to it. To do this, you must first establish or check the concentration of ORIGINAL ACIDS by determining the H2SO4 content in THEM.
By adding water to a concentrated acid (oleum or monohydrate), you can get an acid of any concentration, but when mixing it is concentrated. Sulfuric acid and water release a large amount of heat. The acid may heat up to a boil, a violent release of vapors will occur, and the solution may be ejected from the vessel. Therefore, acids are mixed in special apparatus - mixers, taking appropriate precautions.
Mixers for preparing low concentration acid are made of acid-resistant material, for preparing concentrated acid - from cast iron. Mixers of various designs are used in sulfuric acid. In some cases, the mixer is made of cast iron, enameled on the inside, placed in a steel casing and closed with a lid. The mixed acids enter a cast iron cone enameled on both sides, in which they are mixed, after which they flow into the boiler. To remove the heat generated when mixing acids, a stream of water is continuously supplied into the space between the boiler and the casing, washing the walls of the apparatus.
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 diluted 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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