The molar heat capacities of P, Q and R are in the ratio 2:3:4. For the reaction P + Q → R the enthalpy change at temperature T 1 is ΔH 1 . Assuming the heat capacities do not vary with temperature, t

Question

The molar heat capacities of P, Q and R are in the ratio 2:3:4. For the reaction P + Q → R the enthalpy change at temperature T 1 is ΔH 1 . Assuming the heat capacities do not vary with temperature, the enthalpy change ΔH 2 at T 2 (T 2 > T 1 ) will be

TestHub · Accepted Answer

ΔC P = C P (R) - C P (P) - C P (Q) = 4 - 2 - 3 = -1 unit. Then ΔH 2 = ΔH 1 + ΔC P (T 2 - T 1 ) = ΔH 1 - (T 2 - T 1 ), and since T 2 > T 1 , ΔH 2 < ΔH 1 . This is option (a).

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