Question

If 27.37ml of 0.2115M NaOH is able to neutralize 37.45 of HCl, what is the concentration of the acid?

Answer 1

You just gotta match the moles:

moles of NaOH = 0.02737 L * 0.2115 M = 0.005789 mol of NaOH. The amount of moles of HCl it can neutralize should be the same since they are in a 1:1 ratio. Therefore, you can do moles of NaOH divided by 0.003745L to get the answer. It turns out to be 0.1546M.