Chapter 25

An accurately weighed amount \((3.6284 \mathrm{~g}\) ) of hydrated sodium carbonate \(\left(\mathrm{Na}_{2} \mathrm{CO}_{3} \times \mathrm{H}_{2} \mathrm{O}\right)\) was dissolved in water \((250.00 \mathrm{~mL}\) ). An aliquot \((25.00 \mathrm{~mL})\) of this solution required hydrochloric acid solution \((25.4 \mathrm{~mL} ; 0.100 \mathrm{M})\) for equivalence. Calculate the number of molecules of water of crystallisation \((x)\) in the original hydrated sodium carbonate. (HINT: you need to calculate \(M_{\mathrm{r}}\) for the original \(\left.\mathrm{Na}_{2} \mathrm{CO}_{3} \times \mathrm{H}_{2} \mathrm{O} .\right)\)