Calculate the standard heat of formation of Cu2O(s) given the reactions 1. 2Cu2O(s)+O2(g)4CuO(s) delta HCu2O(s) delta H

Question

Calculate the standard heat of formation of Cu2O(s) given the reactions 1. 2Cu2O(s)+O2(g)>>>4CuO(s) delta H<<-288.0kj 2. CuO(s)+Cu(s)>>>Cu2O(s) delta H<<<-11.3 kJ

dtan5457 · Answer

@Abhisar @aaronq

aaronq · Answer

The Hf's for O2 and Cu are zero, so you have:

1) $ \sf ΔH_1=4H_f(CuO)−2H_f(Cu2O)$

2) $\sf ΔH_2=H_f(Cu2O)−H_f(CuO)$

Now it's a matter of solving the system of equations

1) $\sf \dfrac{ΔH_1+2H_f(Cu_2O)}{4}=H_f(CuO)$

Plug into 2)

2) $ \sf ΔH_2=H_f(Cu_2O)−\dfrac{ΔH_1+2H_f(Cu_2O)}{4}$

Rearrange to solve for $H_f(Cu_2O)$

2) $ \sf ΔH_2+\dfrac{ΔH_1}{4}=H_f(Cu_2O)-2H_f(Cu_2O)$

$\sf H_f(Cu_2O)=-[ΔH_2+\dfrac{ΔH_1}{4}]$

dtan5457 · Answer

Forgot about this question..got it now. thanks