Chemical elements connect with each other in strictly certain quantitative ratios. For this reason there were such concepts as an equivalent and equivalent weight. ("Equivalent" in literal translation means "equal", "equivalent"). What is an equivalent in chemical sense of this word? How to calculate an equivalent and (or) equivalent weight?
Instruction
1. Equivalents and equivalent masses usually are defined or according to the analysis of connections, or on the basis of results of replacement of one element by another. It is easy to understand that for definition of an equivalent (or equivalent weight) an element it is optional to proceed from its connection with hydrogen at all. The equivalent (equivalent weight) can be calculated likewise on structure of connection of this element with any other, the equivalent (equivalent weight) of which is known.
2. Example. At connection 1.50 grams of sodium a lot of chlorine was formed 3.81 grams of chloride of sodium. It is necessary to find the equivalent mass of sodium and its equivalent if it is known that the equivalent mass of chlorine is equal 35.45 grams/mol. Decision. Subtract the initial mass of sodium from the lump of the formed product. Thus, 3, 81 – 1, 50 = 2, 31
3. That is, in the formed product (in your case sodium chloride) 2.31 grams of chlorine are the share of 1.50 grams of sodium. It follows from this that knowing the equivalent mass of chlorine (35, 45 grams/mol), you will easily find the equivalent mass of sodium on the following formula: 35, 45 x 1, 50/2, 31 Equivalent mass of sodium turn out equal 23.0 grams/mol.
4. The molar mass of sodium will also be equal 23.0 grams/mol. It follows from this that the equivalent of sodium is equal to one I ask (as the molar and equivalent mass of sodium coincides).
5. The concept about equivalents and equivalent masses extends as well to complex substances. An equivalent of complex substance is called its such quantity which interacts without the rest with one equivalent of hydrogen.