In a titration, 16.02 mL of 0.100M NaOH was required to titrate 0.2011 g of an unknown acid, HX. What is the molar mass of the acid?

1 Answer
Nov 8, 2015

Answer:

We assume the acid to be monoprotic.

Explanation:

Rxn: #HX(aq) + NaOH(aq) rarr H_2O(l) + NaX(aq)#

Therefore, moles of NaOH used #-=# moles of HX, the unknown acid.

Moles of NaOH:#16.02xx10^(-3)Lxx0.100*mol*L^(-1)=16.02xx10^(-4)* mol#.

Thus your sample mass represents #16.02xx10^(-4)*mol#.

The molar mass is simply the quotient, #(0.2011*g)/(16.02xx10^(-4)*mol)#, about #120*g*mol^(-1)?# At least I know it is right dimensionally, which is why I pfaff about with the units.