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.
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728 questions · page 16 of 37
- A. Total heat
- B. Volume
- C. Entropy
- D. Internal energy
Explanation: In an isochoric process, also known as an isovolumetric or constant volume process, the volume of the system remains constant throughout…
Correct answer: Volume- A. Activation Energy
- B. Internal energy change
- C. Entropy
- D. Enthalpy
Explanation: Enthalpy is the measure of total heat present in a system under constant pressure. It takes into account both internal and external heat.
Correct answer: Enthalpy- A. Charge to size ratio
- B. Polarizability of anions
- C. Polarization power of Cations
- D. All of these
Explanation: Hydration energy is the amount of energy released or absorbed when ions in gaseous state are surrounded by water molecules to form…
Correct answer: All of these- A. By spectrometry
- B. By conductometry
- C. By calorimetry
- D. By refractometry
Explanation: Calorimetry is used to measure amounts of heat change.
Correct answer: By calorimetry- A. Entropy
- B. Heat
- C. Enthalpy
- D. Temperature
Explanation: Correct option is C. Enthalpy, a property of a thermodynamic system, is the sum of the system's internal energy and the product of its…
Correct answer: Enthalpy- A. Latent heat of fusion
- B. Latent heat of vaporization
- C. Latent heat of sublimation
- D. All of these
Explanation: Correct option is B. This option is correct because steam has more warmth and vitality than water.
Correct answer: Latent heat of vaporization- A. System
- B. Surroundings
- C. Boundary
- D. Universe
Explanation: Endothermic reactions are the ones that need the energy to proceed. This energy in the form of heat is absorbed from the surroundings.
Correct answer: Surroundings- A. Nitrogen gas
- B. Ethene
- C. Water
- D. All have the same heat of vaporization
Explanation: The heat of vaporization is defined as the amount of heat required to convert 1g of a liquid into vapors, without any change in…
Correct answer: Water- A. Mg⁺²
- B. Ca⁺²
- C. Be⁺²
- D. Sr⁺²
Explanation: The hydration enthalpy becomes smaller as the size of the ion increases.
Correct answer: Be⁺²- A. 273 K
- B. 212 F
- C. 273 C
- D. 298 K
Explanation: Bond enthalpy is the energy change at 25 oC or 298 K.
Correct answer: 298 K- A. Work done
- B. Entropy
- C. Potential energy
- D. Kinetic energy
Explanation: The correct option is A) Work done. Enthalpy is the sum of internal energy and the work done on or by the system.
Correct answer: Work done- A. Initial conditions
- B. Final conditions
- C. Initial and final conditions
- D. Path of the reaction
Explanation: Volume is a state funtion which means that it depends only on the the initial and final conditions and is independent of the path followed.
Correct answer: Initial and final conditions- A. 1
- B. 10
- C. 1/e
- D. 2.718
Explanation: ∆rGº = - 8.314 × 103∴- ∆rGº = 8.314 × 103 = RT ln Keqor 8.314 × 103 = 8.314 × 103 ln Keqor ln Keq = 1 = ln e or Keq = e = 2.718
Correct answer: 2.718- A. -143 KJ
- B. -286 KJ
- C. Zero
- D. +286 KJ
Explanation: The calorific value of H2(g) at STP is given as 12.78 kJ/L. At STP, 1 mole of gas occupies 22.4 L.
Correct answer: -286 KJ- A. Buffer
- B. Transition Zone
- C. Boundary
- D. Intermediate state
Explanation: Option A: A buffer is a solution that helps maintain a stable pH level by resisting changes in acidity or alkalinity.
Correct answer: Boundary- A. Total energy
- B. Kinetic Energy
- C. Potential Energy
- D. Internal Energy
Explanation: Internal energy is defined as the total energy of a closed system.
Correct answer: Internal Energy- A. NA+ R
- B. R/NA
- C. NA/R
- D. NA*R
Explanation: The Boltzmann constant (k or k_B) is a physical constant that relates the average kinetic energy of particles in a gas with the…
Correct answer: R/NA- A. Energy content of product is more
- B. Energy content of reactant is less
- C. Heat is transferred from the system to surrounding
- D. Heat is transferred from the Surrounding to the system
Explanation: The correct option is C) Heat is transferred from the system to surrounding.
Correct answer: Heat is transferred from the system to surrounding- A. Spontaneous Reaction
- B. Exothermic Reaction
- C. Reversible Reaction
- D. Endothermic Reaction
Explanation: The correct answer is Endothermic Reaction. The conversion of water into steam involves the absorption of heat energy to overcome the…
Correct answer: Endothermic Reaction- A. Surrounding from the environment
- B. Reactants from contamination
- C. System from surrounding
- D. Products from the surrounding
Explanation: By definition, the real or imaginary surface separating the system from the surroundings is called the boundary.
Correct answer: System from surrounding