the acid base reaction equation is as follows;
HCl + NaOH ---> NaCl + H₂O
stoichiometry of HCl to NaOH is 1:1
NaOH is a strong base and HCl is a strong acid they completely dissociate into its ions
number of HCl moles - 0.16 mol/L x 0.200 L = 0.032 mol
number of NaOH moles - 0.091 mol/L x 0.300 L = 0.0273 mol
Limiting reactant is NaOH therefore number of HCl moles reacted - 0.0273 mol
the excess amount of HCl moles are - 0.032 - 0.0273 = 0.0047 mol
since HCl is a strong acid
total volume - 200 mL + 300 mL = 500 mL
[HCl ] = [H⁺]
therefore [H⁺] = 0.0047 mol / 0.500 mL
[H⁺] = 0.0094 mol/L
hydroxide ion concentration - 0.0094 M
