Answer to Question #146136 in General Chemistry for Godswill

Question

2g of a mixture of sodium hydroxide and sodium(as impurity)were dissolved in 500cmcube of water. If 25cmcube of this solution were neutralized by 21cm.0.1moledm-cube hydrochloric acid. Calculate the percentage of the sodium chloride impurity.

Answer 1

Given:

m_mixture(NaOH;Na)=2g

V(HCl)=21 cm³;

M(HCl)= 0.1 M

Find: % impurity

NaOH + HCl --> NaCl + H₂O ;

n(HCl)=n(NaOH)=0.1*21/1000=0.0021 mole;

Mass of NaOH in 25 cm³:

m(NaOH)=0.0021*40=0.084 g;

Mass of NaOH in 500 cm³:

m(NaOH)= 0.084*500/25=1.68 g

m(impurity)=2 - 1.68=0.32 g

%impurity =0.32/2*100%=16%

Answer: 16%