Situations in which the same formulas receive different names as it is impossible to establish exact authorship or superiority of opening are frequent. And for finding of density with a pressure and temperature the formula bearing names at once of two prominent scientists - Mendeleyev and Clapeyron is used.
Instruction
1. Remember a general view of the equation which is necessary for you for calculation of density on the set temperature and pressure. The standard form of record of the equation of Clapeyron-Mendeleyev for a condition of ideal gas looks as follows: p*V = R*T. Respectively, in the left part there is a work of pressure of gas upon its molar volume, and in right – a universal gas constant on temperature.
2. Pay attention to dimension: T - it is absolute temperature measured in Kelvins. Also remember value of a gas constant. For the simplest chemical tasks it is enough to know its rounded value: 8.3 J / Mol*K. In case you forgot this value, it is possible to use a formula for calculation of a gas constant through the work of the constant of Bolzano expressing dependence between temperature and energy (the value is 1.38 J / J) on Avogadro's number (6.022 * 10 in 23 degrees 1/mol). The last contains information on the number of the specified structural units (various particles) which fall on 1 mole of a substance.
3. Use a formula to learn values of molar volume of necessary gas. The received value will allow you to find the required density. For this purpose write down expression of density through the relation of molar mass of gas to its volume that is a simple consequence of determination of density as the relations of mass of a certain body to the volume occupied by him. If it is about substances, then the bodies consisting of these substances mean. Determine molar weight by special tables. If you deal with complex substance, then determine its molar weight through a summation of molar mass of the substances entering it. One more way to perform this operation is to use the calculator of molar weight on the Internet.