10.5g of Zinc trioxocarbonate (iv),were heated very strongly to a constant mass and the residue treated with excess hydrochloric acid. Calculate the mass of Zinc chloride that would be obtained

2 answers

Where did you get that name for ZnCO3? There is no such name. Zinc carbonate is one of the preferred names by IUPAC for ZnCO3. If you obtained that from a text please give me the reference. Please cite your source.
ZnCO3 + heat --> ZnO + CO2, then
ZnO + 2HCl ==> ZnCl2 +H2O
mols ZnCO3 = grams/molar mass = 10.5/? = about 0.08 but that's just a guess. You need to find a more accurate number.
Then 0.084 mols ZnCO3 x (1 mol ZnO/1 mol ZnCO3) x (1 mol ZnCl2/1 mol ZnO) = 0.084 mols ZnCl2.
mass ZnCl2 = mols ZnCl2 x molar mass ZnCl2
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