Guide

1

One of the formulas volume of solution: V = m / p, where V - volume of solution (ml), m - weight (g), p - the density (g / ml).If you want to find a lot further, you can do this, knowing the formula and the number of the desired substance.Using the formula we find the substance of its molar mass, folded atomic weights of all the elements included in its composition.For example, M (AgNO3) = 108 + 14 + 16 * 3 = 170 g / mol.Next, we find the mass according to the formula: m = n * M, where m - weight (g), n - amount of substance (mole), M - molar mass of material (g / mol).It is understood that the number of substances is given in the task.

2

following formula for the volume of the solution is derived from the formula of the molar concentrati
on of the solution a: = n / V, wherein c - molar concentration of solution (mol / l), n - amount of substance (mole), V -volume of the solution (L).We deduce: V = n / c.The amount of substance can be additionally found by the formula: n = m / M, where m - mass, M - molar mass.

3

following are formulas for finding the volume of the gas.V = n * Vm, where V - volume of gas (l), n - amount of substance (mole), Vm - molar volume of gas (l / mol).Under normal conditions, i.e.a pressure equal to 101 325 Pa and a temperature of 273 K molar volume of gas is constant and equal to 22.4 l / mol.

4

to the gas system, there is a formula:: q (x) = V (x) / V, where q (x) (fi) - the volume fraction of the component, V (x) - the amount of the component (L), V - volume of the system (l).This formula can be derived 2 Other: V (x) = q * V, and V = V (x) / q.

5

If in the problem there is the reaction equation, the problem should be solved by means of it.From the equation, you can find the amount of any substance, it is still odd.For example, CuO + 2HCl = CuCl2 + H2O.From this we see that the reaction of 1 mole of copper oxide and 2 moles of hydrochloric acid, to obtain 1 mol of copper chloride and 1 mole of water.Knowing the condition of the problem of the amount of substance of only one component of the reaction can easily find a number of substances.Let the amount of compound copper oxide is 0.3 mol, then n (HCl) = 0.6 mol n (CuCl2) = 0.3 mole, n (H2O) = 0.3 mol.

# Tip 2: How to calculate the volume of the substance

volume - is a quantitative characteristic, indicating what kind of space is occupied by a substance (body).In the SI system volume is measured in cubic meters.How can you find the volume of a substance?

Guide

1

easiest - if you know the exact weight of the substance (M) and density (ρ).Then the volume is in a single action, by the formula:

V = M / ρ.

V = M / ρ.

2

You can use the method, discovered in ancient times the great scientist Archimedes.Surely you know the story of how King Hiero of Syracuse, suspecting her of cheating jeweler ordered Archimedes to determine whether pure gold made him the crown or in the alloy blended cheap impurities.It would seem that everything is simple: know the exact weight of a crown, known to the density of pure gold.But before scientists there was a problem: how to define the scope of the Crown, if it is very complicated in shape?Archimedes solved it brilliantly, crown weighed first in air and then in water.

3

difference in weight - the so-called "buoyancy", equal to the weight of water in the volume of the crown.Well, knowing the density of water, determine the amount of snap.Proceeding similarly, it is possible to determine the amount of any solids, of course, if it is not soluble in water and moreover it does not enter into the reaction.

4

If you are dealing with the gas being under conditions close to normal, then determine its volume is very simple.It is only necessary to remember that one mole of any gas at such conditions, occupies a volume of 22.4 liters.Then you can perform calculations based on the data you conditions.

5

For example, it is necessary to determine how much takes 200 grams of pure nitrogen?First remember formula nitrogen molecule (N2) and the atomic weight of nitrogen (14).The molar weight of nitrogen: 28 grams / mole.That is 22.4 liters would contain 28 grams of gas.And how much will it in 200 grams?Calculate: 200h28 / 22.4 = 250 grams.

6

Well, and how to find the volume of gas, if it is not under normal conditions?Then you come to the aid of the equation Mendeleev-Clapeyron.Although it is derived for the model of an "ideal gas", you can easily use it.

7

Knowing that you need such parameters as the pressure of the gas, its mass and temperature, you calculate the amount of the formula:

V = MRT / mP, where R - universal gas constant, equal to 8.31,m - molar mass of the gas.

V = MRT / mP, where R - universal gas constant, equal to 8.31,m - molar mass of the gas.

Helpful Hint

Put all values into a single system, or get nonsense.

Note

Do not forget the unit!

Sources:

- "Problems in Chemistry", GPKhomchenko, IGKhomchenko, 2002.
- amount by weight of the formula