A 31.5 mL aliquot of HNO3 (aq) of unknown concentration was titrated with 0.0134 M NaOH (ag). It took 23.9 mL of the base to reach the endpoint of the titration. The concentration (M) of the acid was

Answer 1

Start with determining the equation for this reaction

HNO₃ + NaOH -> NaNO₃ + H₂O

Now determine how much NaOH in moles was used in the reaction using factor analysis.

23.9mL NaOH x ((0.0134mol NaOH)/1000mL) = 0.0003202 mol of NaOH

Looking at the reaction equation, for every one mole of NaOH consumed by the reaction, one mole of HNO3 will be consumed. Therefore, there were 0.0003202 moles of HNO₃ in the aliquot used in the reaction.

To determine the concentration of HNO₃, divide the number of moles of HNO₃ by the volume in liters.

(0.0003202 mol HNO₃)/(0.0315 L HNO₃)= 0.01016 M HNO_3.