End PH of a reaction

20cm3 of 0.10moldm-3 hydrochloric acid is added to 10cm3 of 0.10moldm-3 sodium hydroxide. what is the pH of the resulting mixture?

A1.18
B 1.00
C1.48
D1.30

I think first you should work out the moles, but not really sure where to go from there.
The moles would be 0.002 for the HCl, and 0.001 for Na(OH)2.
Then I would divide by volume but which value would I divide by?

Please help.......

Reply 1

Methene

NaOH rather than Na(OH)₂!

So 0.001 moles of HCl would react with 0.001 moles of NaOH, in 1:1 ratio. That leaves you with 0.001 moles of excess HCl which is therefore 0.001 moles of H+ in the solution. Divide that by the volume to get [H+]