Solution is characterized by the volume, concentration, temperature, density and other parameters. Density of solution changes depending on the weight and concentration of the dissolved substance.
Instruction
1. A key formula for density is ρ=m/V where ρ – density, m – the mass of solution, V – its volume. Density can be expressed, for example, in kilograms on liter, or in grams on a milliliter. Anyway, it shows how many substance on weight is the share of unit of volume.
2. The mass of solution consists of the mass of liquid and mass of the substance dissolved in it: m (solution) of =m (liquid) +m (the dissolved substance). The mass of the dissolved substance and volume of solution can be found from the known value of concentration and molar weight.
3. Let, for example, in a task the molar concentration of solution be given. It it is designatedis chemical a connection formula in square brackets. So, record [KOH] of =15 mol/l means that one liter of solution contains the 15th mole of a substance of potassium hydroxide.
4. The molar mass of KOH is 39+16+1=56 g/mol. It is possible to look at the molar mass of elements in Mendeleyev's table, they are specified usually from below from the name of an element. The amount of substance, mass of substance and its molar weight are connected by a ratio ν=m/M where ν – amount of substance (mol), m – weight (g), M – the molar weight (g/mol).
5. Solutions, besides liquid, are also gas. In this case it is necessary to understand that equal volumes of the gas close to ideal, under the same conditions contain the same number of moths. For example, under normal conditions one mol of any gas occupies the volume of Vm=22.4 of l/mol which is called molar volume.
6. In the solution of a task on density of gas solution the ratio establishing connection between amount of substance and volume can be necessary: ν=V/Vm, where ν – amount of substance, V – the volume of solution, Vm – the molar volume, a constant for these conditions. As a rule, in similar tasks it is discussed that conditions are normal (N at.).