Extent of dissociation is the size equal to the relation of quantity of the molecules of substance which broke up to ions to total number of molecules of this substance in solution or fusion.
Instruction
1. Let's assume, set such task for you. There is a liquid ammonia solution with concentration 0.1M. By results of laboratory researches you know that concentration of not dissociated molecules of alcohol is equal to 0.099 mol/litre. What will be degree dissociation?
2. First of all, remember definition of extent of dissociation and a formula on which it is calculated: and = n/N where n is quantity of the molecules of substance which broke up to ions, and N – total number of molecules of substance.
3. After that you will write the equation of electrolytic dissociation of liquid ammonia, it will look as follows: NH4OH = NH4 + + OH-
4. Under the terms of a task the initial molar concentration of alcohol is known. Designate it by letter C. Then concentration of the molecules of alcohol which underwent dissociation designate as the expert. Respectively, and concentration of ions of NH4+ and OH-will also be equal to this size, that is the expert.
5. Define what size the expert is equal to. It is easy to understand that 0.001 mol/litre (you receive this value, having taken away concentration of not broken up molecules from initial concentration of all alcohol). Therefore, required size is: 0.001/0.1 = 0.01. The task is solved. Extent of dissociation of liquid ammonia under the set conditions is equal 0.01 (or 1%, in other calculation).