Question

For the following reaction,

C (diamond) + O2$\longrightarrow$ CO2(g) ; $\Delta$H = –94.3 kcal

C graphite) + O2$\longrightarrow$CO2(g) ; $\Delta$H = –97.6 kcal

The heat required to change 1 g of C (diamond) $\longrightarrow$ C (graphite) is

• A. 1.59 kcal
• B. 0.1375 kcal
• C. 0.55 kcal
• D. 0.275 kcal

Answer 1

Answer: (D)

0.275 kcal

Answer 2

C (diamond) + O2 $\longrightarrow$CO2(g) ; $\Delta$H = – 94.3 kcal

C (graphite) + O2 $\longrightarrow$ CO2(g) ; $\Delta$H = – 97.6 kcal

C (diamond) $\longrightarrow$C (Graphite) $\Delta$H = 3.3 kcal

Heat required to convert 12 gram diamond to graphite = 3.3

$\therefore$ Heat required to convert 1 gm diamond to graphite = $\frac{3.3}{12}$ = 0.275