A sample of pure sodium carbonate 0.318 g is dissolved in water and titrated with HCl solution. A vo

Question

A sample of pure sodium carbonate 0.318 g is dissolved in water and titrated with HCl solution. A volume of 60 mL is required to reach the methyl orange end point. Calculate the molarity of the acid.

Professor PC Thomas Classes · Answer

(a) $\mathrm{Na}_2 \mathrm{CO}_3+2 \mathrm{HCl} \longrightarrow 2 \mathrm{NaCl}+\mathrm{H}_2 \mathrm{O}+\mathrm{CO}_2$ At the equivalent point m-mole of HCl 
$ \begin{aligned} & =2 	imes \mathrm{m} 	ext {-mole of } \mathrm{Na}_2 \mathrm{CO}_3 \ 60 	imes M & =2 	imes \frac{0.318}{106} 	imes 1000 \ M & =0.1 \end{aligned} $