Question

12.5g of zinc trioxocarbonate 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 ?

Answer 1

ZnCO3 ==> ZnO + CO2, then
ZnO + 2HCl ==> ZnCl2 + H2O

mols Zn = grams/atomic mass = 12.5/65.4 = about 0.2 but that's just an estimate. You need to recalculate all of these numbers for a better answer to this question. Looking at the equation 1 mol ZnCO3 produces 1 mol ZnO and 1 mol ZnO produces 1 mol ZnCl2; therefore, 1 mol Zn will produce 1 mol ZnCl2. Thus you will obtain approximately 0.2 mols ZnCl2.
Then grams ZnCl2 = mols ZnCl2 x molar mass ZnCl2 = ?.
Post your work if you get stuck.

Answer 2

12.5/125*136
0.1*136=13.6 answer

Answer 3

12.5

Answer 4

Mass of ZnCO3= mole × molar mass = 1 × 125= 125g
ZnO + 2HCl ZnCl +H2O
If 12.5g of ZnCO3 _ Xg of ZnO
125g of ZnCO3 _ 81g of ZnO
( molar mass of ZnO = 81g)
Therefore Xg of zno _ 12.5g×81 ÷ 125 = 8.1 g of Zno.
So 8.1g of Zno = yg of Zncl2
81g of Zno = 136 of Zncl
( molar mass of zncl2 = 136g)
Therefore yg = 8.1× 136÷ 81 = 13.6g of Zncl2.
So the mass of zncl2 that will be produced is 13.6g.