Thermodynamics Question 8
Question 8 - 2024 (30 Jan Shift 2)
Two reactions are given below:
$2 Fe _{(s)}+\frac{3}{2} O _{2(g)} \rightarrow Fe _2 O _{3(s)}, \Delta H^{\circ}=-822 kJ / mol$
$C _{(s)}+\frac{1}{2} O _{2(g)} \rightarrow CO _{(g)}, \Delta H^{\circ}=-110 kJ / mol$
Then enthalpy change for following reaction
$3 C _{(s)}+Fe _2 O _{3(s)} \rightarrow 2 Fe _{(s)}+3 CO _{(g)}$
Show Answer
Answer (492)
Solution
$2 Fe _{(s)}+\frac{3}{2} O _{2(g)} \rightarrow Fe _2 O _{3(s)}, \Delta H^{\circ}=-822 kJ / mol \ldots$ (1)
$C _{(s)}+\frac{1}{2} O _{2(g)} \rightarrow CO _{(g)}, \Delta H^{\circ}=-110 kJ / mol \ldots$ (2)
$3 C _{(s)}+Fe _2 O _{3(s)} \rightarrow 2 Fe _{(s)}+3 CO _{(g)}, \Delta H _3=$ ?
$(3)=3 \times(2)-(1)$
$\Delta H _3=3 \times \Delta H _2-\Delta H _1$
$=3(-110)+822$
$=492 kJ / mole$
