To calculate amount of substance, learn its weight by means of scales, express it in grams and divide into the molar weight which can be found by means of Mendeleyev's table. In normal conditions apply Avogadro's law to determination of amount of substance of gas. If gas is in other conditions, measure pressure, volume and temperature of gas then calculate amount of substance in it.
It is required to you
- Scales, the thermometer, the manometer, ruler or roulette, the periodic table of Mendeleyev will be necessary for you.
Instruction
1. Determination of amount of substance in a solid body or liquid. Find the mass of the studied body by means of scales, express it in grams. Define of what substance the body consists, then by means of the periodic table of Mendeleyev find the molar mass of substance. For this purpose find the elements which are a part of a molecule of substance of which the body consists. Determine their atomic masses by the table if the fractional number is specified in the table, round it to whole. Find the sum of mass of all atoms entering a substance molecule, receive the molecular weight which is in number equal to the molar mass of substance in grams on mol. After that, divide the weight measured earlier into molar weight. As a result receive amount of substance in moths (υ=m/M).
2. Amount of substance of gas in normal conditions. If gas is normal conditions (0 degrees Celsius and 760 mm Hg.), find its volume. For this purpose measure the volume of the room, a cylinder or a vessel where it is as gas occupies all volume provided to it. To receive its value measure the geometrical sizes of a vessel where it is by means of a roulette and by means of mathematical formulas, find its volume. The most typical case is the room in the form of a parallelepiped. Measure its length, width and height in meters, then multiply them and receive the volume of gas which in it is in cubic meters. To find amount of substance of gas, divide the received volume into number 0.0224 – the molar volume of gas under normal conditions.
3. Amount of substance of gas with any parameters. Measure gas pressure by the manometer in pascals, its temperature in kelvins for what to degrees Celsius in which measures the thermometer add number 273. Determine also gas volume in cubic meters. To find amount of substance the work of pressure and volume divide into temperature and number 8.31 (universal gas constant), υ=PV / (RT).