How to dilute acid with water. Acid solutions

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 to prepare concentrated acid- made of 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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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% directly composed 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 sources nutrition, you should be aware of some differences in 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 source 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 cheap 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 supplies, 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:

• rubber gloves
• chemical-resistant clothing and apron;
• safety 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 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.

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 required quantity 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 the 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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