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Question
If the combustion of 1g of graphite produces 20.7 kJ of heat, what will be molar enthalpy change? Give the significance of sign also.
Solution
Molar enthalpy change for graphite (ΔH)
= enthalpy change for 1 g × molar mass of C = – 20.7 × 12 = – 2.48 × 102 kJ mol–1
Since the sign of ΔH = – ve, it is an exothermic reaction.
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