Add 0.1 M NaOH in 5 mL increments until the pH is reading more than 7. how much did you add?

Answer 1

I'll assume you had 25 mls of 0.1 M HCl, since that is what you had in your previous question. That being the case, you have the following equation for the reaction taking place.

HCl + NaOH ==> NaCl + H2O ... balanced equation

You see it take 1 mol of NaOH for every 1 mol of HCl.

So find the moles of HCl you have:

** 25 mls HCl x 1 L/1000 mls x 0.1 mol/L = 0.0025 mols HCl

** 0.0025 mols NaOH are required to completely neutralize this to pH 7

** Since they are both 0.1 M, it should take an equal volume of 25 mls of NaOH to reach pH 7.

So, to get a pH reading greater than 7 would take more than 25 mls and since you are adding the NaOH in 5 ml increments, it would be 30 mls.