Friday, 23 September 2011
Q5. Excess zinc carbonate is added to hydrochloric acid in the preparation of zinc chloride salt.
(i) Write an ionic equation for the reaction.
Ans: ZnCO3(S)+2H+(aq) = Zn2+(aq)+CO2(G)+H2O(L)
(ii) Why excess zinc carbonate is used?
Ans: It is to ensure that the excess zinc carbonate has completely reacted with hydrochloric acid to form calcium chloride.
(iii) Briefly explains how the zinc chloride crystals can be obtained.
Ans:
First, add the excess zinc carbonate solid to the dilute hydrochloric acid until excess zinc carbonate is formed.
Second, filter to remove the excess unreacted zinc carbonate solid.
Third, evaporate the remaining solution to remove water and make a saturated salt solution.
Last, leave the hot saturated solution to cool down and zinc chloride crystals will be form.
(i) Write an ionic equation for the reaction.
Ans: ZnCO3(S)+2H+(aq) = Zn2+(aq)+CO2(G)+H2O(L)
(ii) Why excess zinc carbonate is used?
Ans: It is to ensure that the excess zinc carbonate has completely reacted with hydrochloric acid to form calcium chloride.
(iii) Briefly explains how the zinc chloride crystals can be obtained.
Ans:
First, add the excess zinc carbonate solid to the dilute hydrochloric acid until excess zinc carbonate is formed.
Second, filter to remove the excess unreacted zinc carbonate solid.
Third, evaporate the remaining solution to remove water and make a saturated salt solution.
Last, leave the hot saturated solution to cool down and zinc chloride crystals will be form.
what we could have been, 06:22.
