Free Thermochemistry and Energetics of Chemical Reactions MCQs with Answers
728 Thermochemistry and Energetics of Chemical Reactions MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Thermochemistry measures energy changes in chemical reactions and distinguishes exothermic from endothermic processes. Work covers systems, surroundings and state functions, internal energy, the first law of thermodynamics, enthalpy and Hess's law, including the sign conventions used when heat enters or leaves a system.
Last updated
728 questions · page 14 of 37
- A. Open system.
- B. Closed system.
- C. Isolated system.
- D. Heterogeneous system.
Explanation: The correct answer is an Isolated system because it does not allow the transfer of energy or matter between the system and its…
Correct answer: Isolated system.- A. One phase.
- B. Two phases.
- C. Three phases.
- D. Any number of phases.
Explanation: A heterogeneous system is one that contains two or more different phases.
Correct answer: Any number of phases.- A. ΔE = q + w
- B. ΔE = q - w
- C. ΔE = q + P ΔV
- D. ΔE = q + ΔH
Explanation: According to the first law of thermodynamics, the change in internal energy (ΔE) of a system is equal to the heat added to the system (q)…
Correct answer: ΔE = q - w- A. Extensive properties.
- B. Intensive properties.
- C. Physical properties.
- D. Chemical properties.
Explanation: The correct answer is Intensive properties. These are properties that do not depend on the amount of material present.
Correct answer: Intensive properties.- A. Intensive properties
- B. Extensive properties
- C. Physical properties
- D. None of the above
Explanation: The correct answer is Extensive properties. These are properties that change when the size of the sample changes.
Correct answer: Extensive properties- A. Surface tension and Viscosity.
- B. Pressure and Density.
- C. Melting and Boiling points.
- D. All of the above.
Explanation: The correct answer is Option D: All of the above. Intensive properties are characteristics of a substance that do not change with the…
Correct answer: All of the above.- A. Composition of the system.
- B. Temperature, Pressure & Volume.
- C. Refractive Index and specific heat.
- D. All of the above properties taken together.
Explanation: The correct answer is Option B: Temperature, Pressure & Volume. In thermodynamics, the state of a system is described by state variables…
Correct answer: Temperature, Pressure & Volume.- A. Isothermal process.
- B. Equilibrium process.
- C. Physical process.
- D. Chemical process.
Explanation: The correct answer is the 'Isothermal process'. In thermodynamics, an isothermal process is one in which the temperature of the system…
Correct answer: Isothermal process.- A. Enthalpy of atomization
- B. Enthalpy of fusion
- C. Enthalpy of vaporization
- D. Enthalpy of formation
Explanation: Option A, enthalpy of atomization, is the energy required to completely separate all the atoms in a chemical substance.
Correct answer: Enthalpy of atomization- A. Enthalpy change of formation of water
- B. Enthalpy change of neutralization
- C. Both; Enthalpy change of combustion of Hydrogen and enthalpy change of formation of water
- D. Enthalpy change of combustion of Hydrogen
Explanation: Since 1 mole of H2 is being combusted, it can be called enthalpy change of combustion of H2.
Correct answer: Both; Enthalpy change of combustion of Hydrogen and enthalpy change of formation of water- A. Enthalpy of combustion
- B. Enthalpy of formation
- C. Enthalpy of atomization
- D. Enthalpy of solution
Explanation: Combustion is an oxidation reaction that produces heat, and it is therefore always exothermic.
Correct answer: Enthalpy of combustion- A. The energy of activation of backward reaction is less than that of forward reaction
- B. The energy of activation of backward reaction is more that that of forward reaction
- C. The energy of activation of forward reaction is less than that of backward reaction
- D. The energy of activation of forward - backward reaction is same
Explanation: In an endothermic reaction, the activation energy of a forward reaction will always be greater than that of the reverse reaction as can be…
Correct answer: The energy of activation of backward reaction is less than that of forward reaction- A. Chemical Equilibrium
- B. Chemical Bonding
- C. Heat contents of a compound
- D. AlI of these options are correct
Explanation: This question has been repeated in multiple other papers, hence indicating that this is a high-yield concept.
Correct answer: Heat contents of a compound- A. -484 KJmol-1
- B. -242 KJmol-1
- C. -121 KJmol-1
- D. +242 KJmol-1
Explanation: To determine the enthalpy change of formation (ΔHf) for one mole of H2O, we can use the given information about the heat evolved in the…
Correct answer: -242 KJmol-1- A. Spontaneous reaction
- B. Non-Spontaneous reaction
- C. First law of thermodynamics
- D. All of the above options are correct
Explanation: In this case:Heat is being transferred from hot surroundings to the cold interior of a refrigerator, which is against the natural…
Correct answer: Non-Spontaneous reaction- A. Endothermic Reaction
- B. Non spontaneous Reaction
- C. Third Order Reaction
- D. Exothermic Reaction
Explanation: Calcium oxide reacts with water to form calcium hydroxide, also called slaked lime.
Correct answer: Exothermic Reaction- A. Joule's Law
- B. Ohm's Law
- C. Hess's Law
- D. Faraday's Law
- E. Boyle's Law
Explanation: Hess' law states that the change of enthalpy in a chemical reaction (i.e.
Correct answer: Hess's Law- A. Pressure is maintained constant
- B. The gas is isothermally expanded
- C. There is perfect heat insulation
- D. System exchanges heat with the surroundings
Explanation: During an adiabatic process, the system is completely insulated from its surroundings.
Correct answer: There is perfect heat insulation- A. Heat of combustion
- B. Heat of formation
- C. Heat of solution
- D. Heat of dilution
Explanation: The enthalpy of reaction for any chemical reaction is equal to the difference between the sum of the enthalpies of the formation of the…
Correct answer: Heat of formation280. The study of measurement of heat absorbed or given out in a chemical reaction is referred to as:
- A. Endothermic reaction
- B. Exothermic reaction
- C. Thermochemistry
- D. Heat of formation
Explanation: Thermochemistry is the branch of chemistry that deals with the measurement and analysis of heat energy changes in chemical processes and…
Correct answer: Thermochemistry