# Advice 1: How to determine the acid strength

Which acid is stronger? The answers to this question is not as simple as it seems at first glance. Depends on what grounds and in what kind of environment to determine the strength of the acid. One should not confuse oxidative and acidic properties of acid – sometimes they may not quite be the same. For example, a mixture of hydrochloric and nitric acids – "Aqua Regia" is one of the most powerful oxidizing agents. But hydrochloric and nitric acid are not the strongest.
You will need
• - reference chemical table.
Instruction
1
From the point of view of the theory of electrolytic dissociation acid is a compound which upon dissociation in water breaks down into positive hydrogen ion and a negatively charged base. From the definition it follows that the degree of dissociation determines the strength of the acid.
2
The degree of dissociation depends on the concentration and is given by the equation: a = SDI/Sobsch, %; where SDIs is the molar concentration predissociative molecules, Sobsch – total molar concentration of the substance taken to prepare the solution. Strong acids dissociate almost completely, acid of moderate strength from 3 to 30%, weak – less than 3 %. As can be seen from the equation, the greater the concentration of a substance in solution, the smaller the value. Knowing the degree of dissociation you can judge the strength of the acid.
3
Force acid is also characterized by the dissociation constant or acidity constant. It is given by the expression: K = [A+]*[B-]/[AB] = const, where [A+] [B-] – equilibrium concentration of ions predissociative, [AB] is the equilibrium concentration narodoslawsky molecules. Of the total molar concentration the dissociation constant is not affected. With increasing temperature the degree and constant of dissociation increase.
4
To determine the strength of the acid, find its dissociation constant in lookup tables. The bigger it is, the stronger the acid. Strong acids have a constant from 43.6 (HNO3) and above. To strong acids is part of the mineral acids: perchloric, hydrochloric, sulphuric and others. The weak acids include organic acids (acetic, malic, etc.) and some mineral (coal, cyanide).
5
Along with the constant is used the pH of the pK, which is equal to a negative decimal logarithm of the constant: pK = - lgK. The strong acids it is negative.
6
But how to determine which of the strong acids are stronger if the degree of their dissociation in water tend to infinity? Such acids are called supercyclone. To compare, they are considered according to the theory of Lewis as electron acceptors. The power of SUPERCOLOR measured in other environments with the interaction properties of a weak base. These environments link the protons of the hydrogen of the acid.

# Advice 2 : How to recognize sulphuric acid

Sulphuric acid, having the chemical formula H2SO4, represents a heavy, dense liquid with a buttery texture. Very hygroscopic, readily miscible with water, be sure to pour acid into water, in no case, not Vice versa. One of the strongest acids, especially in concentrated form and at an elevated temperature. How can we recognize sulfuric acid, among other acids and solutions?
Instruction
1
Get sulfuric acid in various ways, among which the most common is "contact". Raw materials are a variety of sulfur-containing ore, mostly pyrite (iron sulfide, FeS2). In the first stage of the process, as a result of his firing, produces sulfur dioxide SO2. Further, this gas is cleaned of impurities and dust by oxidation is converted into sulfur dioxide SO3, from which it is formed and sulphuric acid H2SO4.
2
For example, you were given a few samples of liquids, among which are the sulfuric acid. First of all, you need to make sure that it is really acid. Of course, in any case not probovala samples to taste. Alternately to each tube add a piece of zinc. Those tubes which immediately starts a violent reaction with evolution of gas, are likely to contain acid.
3
Why do you want to use zinc, not alkaline or alkaline-earth metal? Yes, because they are likewise supplanted and hydrogen from pure water and from a solution of some salt. Instead of clarity you'd only be confused. Zinc allows you to determine exactly acid.
4
Separate them from the rest of the samples and look for where it is sulfuric acid. To do this, use a distinctive qualitative reaction on the sulfate ions. Dobaviti each tube a solution of barium chloride (BaCl2). Reacts with sulfuric acid, it immediately forms a dense white precipitate of barium sulfate (BaSO4), according to this scheme:
BaCl2 + H2SO4 = BaSO4 + 2HClВыпадение of this precipitate indicates the content of sulfuric acid in the sample.
Sulfuric acid finds such wide application in different areas, which rightly bears the unofficial title of "blood chemistry". Sulfuric acid used for production of synthetic fibres, fertilizers and explosives, in the production of detergents and pharmaceuticals, as an electrolyte in acid batteries in the processing of metals and leather, petroleum and textile industry. Finally, it is indispensable in many types of organic synthesis, as sulfureuse agent, as a substance that takes water.

# Advice 3 : How to recognize hydrochloric acid

Muriatic, or hydrochloric, acid has the formula HCl. To recognize it in several ways. It is necessary to use some physical and chemical properties of this compound.
Instruction
1
First, make sure that the test solution is acid. The most basic method to achieve the goal - to use the indicator. For example, litmus and methyl orange in acidic environment will turn red, the phenolphthalein will remain white.
2
Next, examine what is available to your look. Hydrochloric acid fumes (there is light white smoke, similar to steam), particularly in the humid air. Looking closely, you will definitely notice this property. Just do not forget about caution, or risk getting a burn on the skin, mucous membranes or respiratory tract. In addition, this compound has a sharp unpleasant odor. But if you decide to use such a sign, be sure to observe the safety precautions (careful strokes the palm direct the air to himself, not stoop to the container and do not inhale deeply).
3
Then take a small glass (subject) and place two drops of one of the studied acid and the other ammonia solution (ammonia). If the acid salt, there will be white smoke (hydrochloric acid in the amount of one drop to soar). Following reaction takes place with the formation of ammonium chloride: NH3 + HCl → NH4Cl.
4
You can also use another chemical property. To carry out the reaction of interaction with strong oxidizing agents (potassium permanganate, manganese dioxide), which is accompanied by release of chlorine gas: 2KMnO4 + 16HCl → 5Cl2↑ + 2MnCl2 + 2KCl + 8H2O. A slight odor of chlorine will help you to determine.
5
Use the demonstration method is the reaction with silver nitrate. The tube containing the unknown acid add 2-3 drops of silver nitrate (AgNO3 leaves the skin with black spots, so work better with gloves). The appearance of a white precipitate, resembling cottage cheese, will clearly indicate the presence of chloride ion. The reaction proceeds as follows: AgNO3 + HCl = AgCl ↓ (cheesy white precipitate) + HNO3. After some time, the sediment hardens, forming plaque on the walls of the tube.

# Advice 4 : How to determine the acid strength

Which acid is stronger? The answers to this question is not as simple as it seems at first glance. Depends on what grounds and in what kind of environment to determine the strength of the acid. One should not confuse oxidative and acidic properties of acid – sometimes they may not quite be the same. For example, a mixture of hydrochloric and nitric acids – "Aqua Regia" is one of the most powerful oxidizing agents. But hydrochloric and nitric acid are not the strongest.
You will need
• - reference chemical table.
Instruction
1
From the point of view of the theory of electrolytic dissociation acid is a compound which upon dissociation in water breaks down into positive hydrogen ion and a negatively charged base. From the definition it follows that the degree of dissociation determines the strength of the acid.
2
The degree of dissociation depends on the concentration and is given by the equation: a = SDI/Sobsch, %; where SDIs is the molar concentration predissociative molecules, Sobsch – total molar concentration of the substance taken to prepare the solution. Strong acids dissociate almost completely, acid of moderate strength from 3 to 30%, weak – less than 3 %. As can be seen from the equation, the greater the concentration of a substance in solution, the smaller the value. Knowing the degree of dissociation you can judge the strength of the acid.
3
Force acid is also characterized by the dissociation constant or acidity constant. It is given by the expression: K = [A+]*[B-]/[AB] = const, where [A+] [B-] – equilibrium concentration of ions predissociative, [AB] is the equilibrium concentration narodoslawsky molecules. Of the total molar concentration the dissociation constant is not affected. With increasing temperature the degree and constant of dissociation increase.
4
To determine the strength of the acid, find its dissociation constant in lookup tables. The bigger it is, the stronger the acid. Strong acids have a constant from 43.6 (HNO3) and above. To strong acids is part of the mineral acids: perchloric, hydrochloric, sulphuric and others. The weak acids include organic acids (acetic, malic, etc.) and some mineral (coal, cyanide).
5
Along with the constant is used the pH of the pK, which is equal to a negative decimal logarithm of the constant: pK = - lgK. The strong acids it is negative.
6
But how to determine which of the strong acids are stronger if the degree of their dissociation in water tend to infinity? Such acids are called supercyclone. To compare, they are considered according to the theory of Lewis as electron acceptors. The power of SUPERCOLOR measured in other environments with the interaction properties of a weak base. These environments link the protons of the hydrogen of the acid.
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