In chemistry the concept "mol" is widely used. This such amount of substance in which contains approximately 6.02214*10^23 its elementary particles — molecules, ions or atoms. For simplification of calculations this huge number which is called Avogadro's number is often rounded to 6.022*10^23. The mol is measured in grams.
Instruction
1. To find mole of a substance, it is necessary to remember very simple rule: the mass of one of any substance it is in number equal to its molecular weight, is only expressed in other sizes. And how molecular weight is defined? By means of Mendeleyev's table you learn the atomic mass of each element which is a part of a molecule of substance. Further it is necessary to put atomic masses taking into account the index of each element and the answer will turn out.
2. For example, widely used in rural economy fertilizer, ammonium nitrate (or in a different way ammonium nitrate). Formula of this substance NH4NO3. How to define what it is equal his moth to? First of all write down empirical (that is the general) a substance formula: N2H4O3.
3. Count its molecular weight taking into account the index of each element: 12*2 + 1*4 + 16*3 = 76 and. e. m (atomic units of mass). Therefore, its molar weight (that is the mass of one asking) also is 76, only its dimension: gram/mol. Answer: one mol of ammonium nitrate weighs 76 grams.
4. Let's assume, to you such task is set. It is known that the weight of 179.2 liters of some gas is 352 grams. It is necessary to define how many one mol of this gas weighs. It is known that under normal conditions one mol of any gas or mix of gases occupies the volume, approximately equal 22.4 liters. And you have 179.2 liters. Make calculation: 179.2/22.4 = 8. Therefore, this volume contains 8 moths of gas.
5. Having divided the weight, known under the terms of a task, into number of moles, receive: 352/8 = 44. Therefore, one mol of this gas weighs 44 grams - it is carbon dioxide, CO2.
6. If there is any amount of gas the mass of M concluded in volume of V at the set temperature of T and pressure of P. It is required to determine its molar weight (that is to find what it is equal his moth to). The universal equation of Mendeleyev-Klapeyrona will help to solve a problem to you: PV = MRT/m where m is that molar weight which we should determine, and R is the universal gas constant equal 8.31. Transforming the equation, receive: m = MRT/PV. Having substituted the known sizes in a formula, you will find what the mol of gas is equal to.