Find Enthalpy: 2HCl (aq) + Zn (s) --> H2(g)+ ZnCl2 (aq)

[Chem_Mod]

What is the enthalpy for ?

[Chem_Mod]

The enthalpy of the reaction is (the sum of the enthalpy of products - the sum of the enthalpy of the reactants). In this problem, are the products. The enthalpy formation of any element (in this case is ) is 0 because gives zero. Therefore, [2(-167.16)-0] - [(153.89) + 2(-167.16)] = -153.89 kJ.

[Victor Qiu 1C]

I think the equation is not correct. I think you should use
ΔH_f^o(Zn²⁺)+2ΔH_f^o(Cl^-)-2ΔH_f^o(HCl)
which gives
-153.89 kJ/mol + 2 × (-167.16 kJ/mol) - 2 × (-167.16 kJ/mol)
and the result is
ΔH_r = -153.89 kJ/mol

[Daniela Santana 2L]

In order to find the enthalpy of this reaction, you should find the sum of the products and the sum of the reactants and subtract them (sum of products - sum of reactants). You can find the respective deltaHf value in the chempendix for each compound and multiply it by their coefficient in the reaction(if they have one). I hope this helps!