Thermochemistry | First Year Chemistry Past Papers MCQs | mosaicbro.com

Thermochemistry | First Year Chemistry Past Papers MCQs

7 of 38 questions (Page 1 of 6)

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1 Spontaneous reactions are:
Correct Answer: A
Explanation: Spontaneous reactions are reversible under suitable conditions (equilibrium can be established).
2 The standard heat changes occur at:
Correct Answer: B
Explanation: Standard conditions are 298 K (25°C) and 1 atm pressure.
3 H⁺ + OH⁻ → H₂O; the change in enthalpy for this reaction is called:
Correct Answer: C
Explanation: This is the standard heat of neutralization for strong acid-strong base reactions (-57.3 kJ/mol).
4 The net change in energy in a chemical reaction is same whether it takes place directly or indirectly. This is called:
Correct Answer: C
Explanation: Hess's Law states that enthalpy change is independent of the reaction path.
5 The enthalpy change when one mole of substance is completely burnt in excess of oxygen is called:
Correct Answer: C
Explanation: Heat of combustion is ΔH for complete burning of 1 mole of substance in O₂.
6 Enthalpy change for the reaction: CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g) is called enthalpy of:
Correct Answer: B
Explanation: This is the combustion reaction of methane (ΔH°c = -890 kJ/mol).
7 Standard enthalpies are measured at:
Correct Answer: B
Explanation: Standard enthalpies are reported at 298 K (25°C) unless specified otherwise.
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