Syllabus problem 6B.1

[William_Hora_2H]

The problem states:

The molar concentration of HCl in hydrochloric acid is reduced to 12% of its initial value by dilution. What is the difference in the pH values of the two solutions?

The answer should be 0.92. Could someone explain the calculation provided in the solutions manual?

[tim_villasenor 1k]

So first you can just assume the concentration of HCl is any number. For simplicity purposes lets just assume its 1. Now, they tell us the concentration was reduced to 12% of its value so that tells us that the other concentration would be .12 if our initial is 1. Next, in order to go from concentration to pH you just need to take the negative log. So by taking -log(1) and -log(.12), you will get that there is a difference of .92 in the answers.