Equivalent of any chemical element is called its such quantity which enters interaction with one moths of atoms of hydrogen. Interaction can consist in connection with hydrogen, or its replacement (in replacement reactions). The molar mass of an equivalent of an element is called, respectively, the mass of one of an equivalent.
Instruction
1. To understand how to calculate the mass of an equivalent, review an example. Alkaline metal of lities entered connection with hydrogen, having formed lithium hydride: LiH. It is required to find the mass of an equivalent of this metal.
2. The atomic mass of lithium is 6.94 and. e. m (atomic units of mass), hydrogen – 1.008 and. e. m. For simplification of calculations, round these sizes a little and take them for 7 and 1.
3. So, what mass fraction (mass percent) of both components in this substance? 7/8 = 0.875 or 87.5% for lithium, and 1/8 = 0.125 or 12, 5% for hydrogen. According to the law of equivalents opened by the German chemist I.V. Richter at the end of the 18th century, all substances react with each other in an equivalent ratio, therefore, in your specific case a mass fraction of hydrogen in as much time less mass fraction of lithium how much the equivalent mass of lithium is more than equivalent mass of hydrogen. Therefore, calculate: 0.875/0.125 = 7. The task is solved: the equivalent mass of lithium is equal in its hydride to 7g/mol.
4. Now consider such conditions. Let's assume, some metal (Me) underwent oxidation reaction. It leaked completely, from 30 g of metal 56, 64 g of its oxide as a result turned out. What equivalent mass of this metal?
5. Remember what equivalent mass (ME) of oxygen. Its molecule diatomic, therefore, ME = 8g/mol. How many oxygen contains in the formed oxide? Subtracting the initial mass of metal from oxide lump, receive: 56.64 - 30 = 26.64 g.
6. Under the same law of equivalents, the equivalent mass of metal is defined as the work of equivalent mass of oxygen on fraction size: mass of metal/weight of oxygen. That is 8g/mol * 30/26.64. Having made these calculations, you receive the answer: 9.009 g/mol or in round figures 9 g/mol. Here such is the equivalent mass of this metal.