Question

3 C2H2(g) → C6H6(g) What is the standard enthalphy change ΔHo, for the reaction represented above? (ΔHof of C2H2(g) is 230 kJ mol-1; (ΔHof of C6H6(g) is 83 kJ mol-1;)

Answer 1

Answer: The standard enthalpy change  is -607kJ

Explanation:

The given balanced chemical reaction is,

$3C_2H_2(g)\rightarrow C_6H_6(g)$

First we have to calculate the enthalpy of reaction $(\Delta H^o)$.

$\Delta H^o=H_f_{product}-H_f_{reactant}$

$\Delta H^o=[n_{C_6H_6}\times \Delta H_f^0_{(C_6H_6)}]-[n_{C_2H_2\times \Delta H_f^0_{(C_2H_2)}]$

where,

We are given:

$\Delta H^o_f_{(C_2H_2)}=230kJ/mol\\\Delta H^o_f_{(C_6H_6)}=83kJ/mol$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(1\times 83)]-[(3\times 230)]=-607kJ$

The standard enthalpy change  is -607kJ