ΔHf of BaCO3(s), CO2(g) , HCl(aq) and H2O(l) respectively are –1216, – 393, – 176 and – 286 KJ/mol. Then ΔHf of BaCl2(aq) from BaCO3(s)+ 2HCl(aq) → BaCl2(aq)+ CO2(g)+ H2O(l), ΔH = – QKJ