If you were given a 0.5 M HCl solution and a 0.85 M HCl solution to titrate, which would you expect to require more base to reach neutral pH? Why?

Answer 1

Both acids are HCl (hydrochloric acid). Since one is 0.5 M and the other is 0.85 M, the one that is 0.85 M will contain more moles of HCl acid per unit volume than the other, and so it will require more base to neutralize it.

The net ionic equation for this reaction is simply H⁺ + OH^- ==> H₂O. The more H⁺ that is present, the more OH^- is needed.

Answer 2

The first thing to do with this problem is to look at what is known. The concentrations of two acids are given in Molarity, which happen to be the same acids. The concentration here pertains to moles/L. Since they are the same acids and the concentration is provided, you can determine which is more acidic or has a lower pH. The more acidic solution will be the solution that will need more base to get to neutral.