Given these reactions, where x represents a generic metal or metalloid 1 ) h 2 ( g ) + 1 2 o 2 ( g ) ⟶ h 2 o ( g ) δ h 1 = − 241.8 kj 2 ) x ( s ) + 2 cl 2 ( g ) ⟶ xcl 4 ( s ) δ h 2 = + 461.9 kj 3 ) 1 2 h 2 ( g ) + 1 2 cl 2 ( g ) ⟶ hcl ( g ) δ h 3 = − 92.3 kj 4 ) x ( s ) + o 2 ( g ) ⟶ xo 2 ( s ) δ h 4 = − 789.1 kj 5 ) h 2 o ( g ) ⟶ h 2 o ( l ) δ h 5 = − 44.0 kj what is the enthalpy, δ h , for this reaction? xcl 4 ( s ) + 2 h 2 o ( l ) ⟶ xo 2 ( s ) + 4 hcl ( g )

Answer : The enthalpy of the given reaction will be, -1048.6 kJ

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

The main reaction is:

The intermediate balanced chemical reactions are:

(1)    

(2)    

(3)    

(4)    

(5)    

Now reversing reaction 2, multiplying reaction 3 by 4, reversing reaction 1 and multiplying by 2, reversing reaction 5 and multiplying by 2 and then adding all the equations, we get :

(1)    

(2)    

(3)    

(4)    

(5)    

The expression for enthalpy of main reaction will be:

Therefore, the enthalpy of the given reaction will be, -1048.6 kJ