Suppose you put in front of such a task.There is a solution of ammonia at a concentration of 0.1M.According to the results of laboratory tests do you know that the concentration of undissociated molecules of alcohol is equal to 0.099 mol / liter.What will be the degree of dissociation ?
First of all, remember to determine the degree dissociation and the formula by which it is calculated: a = n / N, where n - number of molecules of the substance, broken into ions and N - the total number of molecules of the substance.
Then write the equation of the electrolytic dissociation ammonia, it would look like this: NH4OH = NH4 + + OH-
Under the terms of the problem is known initial molar concentration of alcohol.Label it with the letter C. Then, the concentration of the alcohol molec
ules undergoing dissociation , designate as a speaker.Accordingly, the concentration of NH4 + ions and OH- will also be equal to this value, i.e. AC.
Determine what is the value of the AU.It is not difficult to understand that 0.001 mol / liter (you get this value by subtracting from the initial concentration of total alcohol concentration is not broken molecules).Consequently, the desired value is: 0.001 / 0.1 = 0.01.The problem is solved. degree dissociation of ammonia under specified conditions is equal to 0.01 (or 1%, in another year).
Try to remember a simple rule: the closer the degree of dissociation to unity (or 100%), the more electrolyte, the closer to zero - the weaker.
If electrolyte is strong, it is exposed to a significant portion of the dissociation of its molecules (in some cases, virtually all).Accordingly, the weaker the electrolyte, the less its molecules dissociate into ions.The criterion for assessing the strength of the electrolyte is the degree of dissociation.
- how to calculate the degree of dissociation