#5

EXCESS ZINC CARBONATE IS ADDED TO HYDROCHLORIC ACID IN THE PREPARRATION OF ZINC CHLORIDE SALT. 

(i) Write an ionic equation for this reaction


ZnCO3 (aq) + 2HCl (aq) à  ZnCl (aq) + H2O (l) + CO2 (g)








(ii) Why is excess Zinc Carbonate used? 


This is to ensure that ALL Zinc Carbonate has completely neutralized with the acid before we filter out the excess unreacted solid from the salt solution.








(iii) Briefly explain how the Zinc Chloride Crystals can be obtained


Excess ZnCO3 will be added to HCl until a black, insoluble unreacted solid can be seen. Filtration is carried out to remove the excess unreacted solid. The solution of reacted and neutralized solution then undergoes evaporation to remove the water and make a saturated salt solution. The hot saturated solution is left to cool to obtain the zinc chloride crystals.