Question

26.2 mL of a 0.450 M hydrochloric acid solution is titrated with an unknown concentration of sodium hydroxide. 45.8 mL of the sodium hydroxide solution is required to reach the equivalence point. What is the molar concentration of the sodium hydroxide solution?

Answer 1

Answer:

$\large \boxed{\text{0.257 mol/L}}$

Explanation:

(a) Balanced equation

NaOH + HCl ⟶ NaCl + H₂O  

(b) Moles of HCl

$\text{Moles} = \text{26.2 mL} \times \dfrac{\text{0.450 mmol}}{\text{1 mL}} = \text{11.79 mmol}$

(c) Moles of NaOH

$\text{Moles of NaOH} = \text{11.79 mmol HCl} \times \dfrac{ \text{1 mmol NaOH} }{\text{1 mmol HCl}} = \text{11.79 mmol NaOH}$

(d) Molar concentration of NaOH

$c = \dfrac{\text{moles of solute}}{\text{litres of solution}}\\\\c = \dfrac{ n }{ V}\\\\c= \dfrac{ \text{11.79 mmol}}{\text{45.8 mL}} = \text{0.289 mol/L}\\\\\text{The molar concentration of the NaOH is \large \boxed{\textbf{0.257 mol/L}}}$