Question

If 22.50 mL of a sodium hydroxide solution is necessary to neutralize 18.50 mL of a 0.1430 M HNO3 solution, what is the concentration of the NaOH? (Report your answer in molarity.)

Answer 1

The concentration  of NaOH  is  calculated   as follows

calculate the moles of HNO3

moles =molarity x volume
        =18.50 x0.1430 = 2.6455  moles

write  the  reacting  equation
that is
NaOH + HNO3 =NaNO3 +H2O
by  use  mole ratio between NaOH: HNO3 the  moles  of NaOH  is also 2.6455moles

concentration  is therefore moles/volume
= 2.6455/ 22.50 = 0.118M