Density is one of the most important parameters of a physical body. According to definition, density is a scalar size which is measured for uniform bodies in the form of the body weight relation to its volume. There are several ways to learn value of this parameter.
It is required to you
- - scales;
- - volumetric glass;
- - table of volumes.
Instruction
1. Proceeding from definition to learn density, you need to find out the weight and volume of a body. It ruled fairly for solid and liquid substances. Put a body on scales, and you will see a quantitative index necessary for you. Transfer the received value to kilograms which are the main unit in measuring system. If you learn the mass of liquid substance, then before filling in it in a flask and to weigh, learn the mass of the flask. You will need to take away it from the received result.
2. If the body which density you want to find represents the correct geometrical figure, it will be much simpler to work to you. To find the volume of the correct figure, it is possible to use the table of volumes, to find a formula and to calculate on it result. If a figure wrong, take a volumetric glass and fill it with water (not completely). Write down on what mark there is water. Then lower the studied body in water and note figure on which there is water now. The difference between the second and first value will also be the volume necessary for you. The volume of liquid can also be measured by means of the same measured glass.
3. You need only to substitute the obtained data in a formula ρ = to m/V where m is a weight, and V – substance volume.
4. Density of gases is in a different way. For this purpose you will need to know the molar mass of gas and its normal volume. If, according to a statement of the problem, actions take place under normal conditions (temperature of 0 degrees and pressure of 760 mm Hg), then normal volume will be equal to 22.4 l/mol. Molar weight is a mass of one mole of a substance. The formula of finding of density of gas will be ρ = M/V of norms.
5. If temperature or pressure differ from normal, then for clarification of density of gas you should use Klapeyrona-Mendeleyev's formula and to find gas volume: ρ* V = m/M * R*T where ρ is pressure, V – the volume necessary for you, m – the mass of gas, M – molar weight, T – temperature in Kelvins, and R – a universal gas constant which is equal to 8.3 J / mol*k.