Guide

1

most common in the problems of the formula: V = n * Vm, where V - volume of gas (l), n - amount of substance (mole), Vm - molar volume of gas (l/ mol), under normal conditions (n.u.) is the standard size and is 22.4 liters / mole.It so happens that in the circumstances there is no amount of the substance, but there are lots of certain substances, then proceed as: n = m / M, where m - mass of the substance (g), M - molar mass of the substance (g / mol).The molar mass is the table D.Mendeleev: written under each element of its atomic weight, add up all the masses and obtain needed us.But such problems are rare, usually the problem is present in the reaction equation.The solution of such problems on this little change.Consider an example.

2

What volume of hydrogen released during normal conditions, if the aluminum solution weighing 10.8 grams in excess of hydrochloric acid.

Write the reaction equation: 2Al + 6HCl (huts.) = 2AlCl3 + 3H2.

solve the problem of this equation.We find the number of aluminum material, which entered into reaction: n (Al) = m (Al) / M (Al).To substitute data in this formula, we need to calculate the molar mass of aluminum: M (Al) = 27 g / mol.Substitute: n (Al) = 10,8 / 27 = 0.4 mol.Iz equation, we see that by dissolving 2 mol of aluminum produced 3 moles of hydrogen.We expect the same amount of the substance which forms hydrogen from 0.4 mol of aluminum: n (H2) = 3 * 0.4 / 2 = 0.6 mol.Then substitute the data into the formula for finding the volume of hydrogen: V = n * Vm = 0,6 * 22,4 = 13,44 liters.So we got an answer.

Write the reaction equation: 2Al + 6HCl (huts.) = 2AlCl3 + 3H2.

solve the problem of this equation.We find the number of aluminum material, which entered into reaction: n (Al) = m (Al) / M (Al).To substitute data in this formula, we need to calculate the molar mass of aluminum: M (Al) = 27 g / mol.Substitute: n (Al) = 10,8 / 27 = 0.4 mol.Iz equation, we see that by dissolving 2 mol of aluminum produced 3 moles of hydrogen.We expect the same amount of the substance which forms hydrogen from 0.4 mol of aluminum: n (H2) = 3 * 0.4 / 2 = 0.6 mol.Then substitute the data into the formula for finding the volume of hydrogen: V = n * Vm = 0,6 * 22,4 = 13,44 liters.So we got an answer.

3

If we are dealing with a gas system, then we have this formula: q (x) = V (x) / V, where q (x) (fi) - the volume fraction of the component, V (x) - the amount of the component (A), V - volume of the system (l).For finding the volume of the component receives the formula: V (x) = q (x) * V.And if it is necessary to find the volume of the system, then: V = V (x) / q (x).

# Tip 2: How to find the pressure of an ideal gas

consider ideal gas in which the interaction between the molecules is negligible.In addition to pressure, the gas is characterized by the temperature and volume.The relationships between these parameters displayed in the gas laws.

Guide

1

gas pressure is directly proportional to its temperature, amount of substance, and inversely proportional to the volume of the vessel occupied by the gas.The coefficient of proportionality is the universal gas constant R, which is equal to approximately 8.314.It is measured in Joules divided by mole and kelvin.

2

This provision creates mathematical relationship P = νRT / V, where ν - the amount of substance (mole), R = 8,314 - the universal gas constant (J / mol • K), T - temperature of the gas, V- the volume.Pressure is expressed in Pascal.It can be expressed in atmospheres, with 1 atm = 101.325 kPa.

3

Considered dependence - a consequence of the equation Mendeleev-Clapeyron PV = (m / M) • RT.Where m - mass of gas (g), M - its molecular mass (g / mol), and the fraction m / M results in a number of ν material, or the number of moles.Mendeleev-Clapeyron equation is valid for all gases which are considered acceptable ideal.This is a fundamental physical and chemical gas law.

4

Observing the behavior of an ideal gas, talk about the so-called normal conditions - environmental conditions, which most often have to deal in reality.For normal conditions (STP) assume the temperature of 0 degrees Celsius (or 273.15 degrees Kelvin) and a pressure of 101.325 kPa (1 atm).We found a value which is equal to the volume of one mole of an ideal gas under these conditions: Vm = 22,413 l / mol.This is called the molar volume.Molar volume - one of the basic chemical constants used in problem solving.

5

important to understand that at constant pressure and temperature of the gas also remains unchanged.This remarkable postulate formulated in the law of Avogadro, who argues that the volume of gas is directly proportional to the number of moles.

Note

There are other formulas for finding the volume, but if you want to find the volume of gas only appropriate formulas given in this article.

Sources:

- "Handbook of Chemistry", GPKhomchenko, 2005.
- how to find the amount of work