Question

The value of enthalpy change ($\Delta H$) for the reaction $C_2{H}_{5}O{H}_{\left(l\right)}+3O_{2\left(g\right)}\to 2C{O}_{2\left(g\right)}+3H_2{O}_{\left(l\right)}$ at ${27}^0$C is $-1366.5kJmo{l}^{-1}$. The value of internal energy change for the above reaction at this temperature be:

• A. -1371.5 kJ
• B. -1369.0 kJ
• C. -1364.0 kJ
• D. -1361.5 kJ

Answer 1

The correct option is C -1364.0 kJ

The change in the number of moles of gaseous species $\Delta n=2-3=-1$

$\Delta H=\Delta E+\Delta nRT$

$-1366.5kJ/mol=\Delta E+\left[\right(-1)\times 8.314\times {10}^{-3}kJ/mol/K\times (27+273\left)K\right]$

$\Delta E=-1364.0kJ/mol$

The value of internal energy change for the reaction is $-1364.0kJ/mol$.