Heat of Reaction MCQs

21. In an exothermic reaction, the energy of the products is:

• A) Higher than the reactants
• B) Lower than the reactants
• C) The same as the reactants
• D) Zero
• Answer: B

22. Which of the following terms describes the heat change when one mole of a substance is burned in excess oxygen?

• A) Heat of formation
• B) Heat of combustion
• C) Heat of neutralization
• D) Heat of sublimation
• Answer: B

23. Which of the following has the greatest heat of combustion?

• A) Methane
• B) Ethane
• C) Propane
• D) Butane
• Answer: D

24. In a thermochemical equation, the heat of reaction is written:

• A) As a product
• B) As a reactant
• C) Outside the equation
• D) With the temperature
• Answer: C

25. Which of the following is NOT a factor affecting the heat of reaction?

• A) Concentration
• B) Physical state of reactants
• C) Catalyst
• D) Phase change
• Answer: C

26. The heat of neutralization between a strong acid and a strong base is approximately:

• A) 57 kJ/mol
• B) 75 kJ/mol
• C) 100 kJ/mol
• D) 120 kJ/mol
• Answer: A

27. Which of the following changes the heat of reaction?

• A) Increasing the surface area of reactants
• B) Changing the pressure of a gas
• C) Changing the temperature
• D) Adding a catalyst
• Answer: C

28. The heat released or absorbed during a chemical reaction at constant pressure is called:

• A) Work done
• B) Enthalpy change
• C) Gibbs free energy
• D) Activation energy
• Answer: B

29. What does Hess’s Law state?

• A) The heat of reaction is independent of the path taken
• B) The heat of reaction is directly proportional to pressure
• C) The heat of reaction is inversely proportional to volume
• D) The heat of reaction depends on the speed of the reaction
• Answer: A

30. In an endothermic reaction, the enthalpy of products is:

• A) Greater than that of reactants
• B) Less than that of reactants
• C) Equal to that of reactants
• D) Zero
• Answer: A