Chemistry - Thermochemistry Question with Solution | TestHub
Statement 1: On increasing the temperature, enthalpy of reaction may increase, decrease or remain constant.
Statement 2: On changing the temperature, the enthalpies of reactants and products may change to same or different extent depending on their heat capacities.
Options:
Answer:
Solution:
According to Kirchhoff's law, Δ H(T2) = Δ H(T1) + ∫ Δ CP dT. Since Δ CP can be positive, negative, or zero, the Δ H of a reaction may increase, decrease, or remain constant upon heating. Therefore, Statement 1 is correct.
The enthalpy of each substance changes with temperature according to its own heat capacity, as described by dH = CP dT. This means that reactants and products shift by the same or different extents, which explains why Δ H can change in any direction. Thus, Statement 2 is correct and provides an explanation for Statement 1.
The answer is (a).
