Hess’s Cycle Question 10

The bombardier beetle can fire a hot, toxic mixture of chemicals when they feel threatened. The mixture containes C₆H₄O₂, a compound that can be formed using the following equation:

$C_6H_4(OH)_{2(aq)}+H_2O_{2(aq)}\rightarrow C_6H_4O_{2(aq)}+2H_2O_{(l)}$

Use the following data to calculate the enthalpy change for the above reaction:

$C_6H_4(OH)_{2(aq)}\rightarrow C_6H_4O_{2(aq)}+H_2{(g)}\: \: \: \Delta H:\: 177.4kJ\: mol^-^1$

$H_{2(g)}+O_{2(g)}\rightarrow H_2O_{2(aq)}\: \: \: \Delta H:-191.2kJ\: mol^-^1$

$H_{2(g)}+\frac{1}{2}O_{2(g)}\rightarrow H_2O_{(l)}\: \: \: \Delta H:-286kJ\: mol^-^1$

$clockwise = anticlockwise$

${\color{Red} x}+{\color{Pink} (-191.2)} = {\color{Blue} 2(-286)}+{\color{Magenta} 177.4}$

$x=-203.4kJ$