20cm cube of 0.1M HCL exactly neutralized 25cm cube of sodium hydroxide solute . what's molar concentration of alkali

Answer 1

HCl + NaOH ==> NaCl + H2O
I don't like to work in moles with this type problem for the zeros are easy to get mixed up; i.e.,
mols HCl = M x L = 0.1 x 0.020 = 0.0020 so I work in millimoles.
millimoles HCl = mL x M = 20 mL x 0.1 M = 2
From the equation you see 1 mol HCl = 1 mol NaOH; therefore, there are 2 millimoles NaOH.
Then millimoles NaOH = mL x M so M = millimols NaOH/mL NaOH = 2/25 = 0.08 M NaOH