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 7 of 37
- A. Surroundings
- B. Boundaries of the system
- C. Only within the system
- D. All of these
Explanation: Heat is the energy that flows across the boundaries of the system. This means that heat can flow into or out of the system, but it cannot…
Correct answer: Boundaries of the system- A. Surrounding from the environment
- B. Reactants from contamination
- C. System from surrounding
- D. Products from the surrounding
Explanation: In thermodynamics, a boundary separates a system from its surroundings. A system is a collection of matter and energy that is under study.
Correct answer: System from surrounding- A. Surroundings
- B. System
- C. State of a system
- D. All of these
Explanation: In thermodynamics, the state of a system is described by a set of properties that define its condition at a given point in time.
Correct answer: State of a system- A. Water
- B. Water in cup
- C. Whole table
- D. All of these
Explanation: In thermodynamics, a state of matter that is confined by some walls in space and separated from surroundings by those walls is called a…
Correct answer: Water- A. AI2O3
- B. B2O3
- C. CO
- D. All of these
Explanation: Standard enthalpies of formation (∆Hf) for certain compounds, such as Al2O3 (aluminum oxide), B2O3 (boron oxide), and CO (carbon…
Correct answer: All of these- A. Spontaneous reaction
- B. Exothermic reaction
- C. Endothermic reaction
- D. Non-spontaneous reaction
Explanation: A reaction that does not occur in nature is often referred to as a "non-spontaneous" or "non-natural" reaction.
Correct answer: Non-spontaneous reaction- A. Route taken by reaction for completion
- B. Temperature of reactants
- C. Concentration of products
- D. Concentration of reactants
Explanation: Hess's law states that the total enthalpy change of a reaction remains the same regardless of the route taken by the reaction for…
Correct answer: Route taken by reaction for completion- A. Same for all the routes of that reaction
- B. Different for different routes of that reaction
- C. Depends up on the reactants present in each route
- D. None of these
Explanation: Option A is correct since it states the correct definition of Hess's law which is: If a chemical change takes place by several different…
Correct answer: Same for all the routes of that reaction- A. Boiling point
- B. Chemical bonding
- C. Quantum study
- D. Physical properties
Explanation: Knowledge obtained through thermodynamics is used to explain: d) Physical properties Thermodynamics provides insights and explanations for…
Correct answer: Physical properties- A. Unity
- B. Zero
- C. Positive
- D. Negative
Explanation: In a cyclic process the net change in internal energy is zero because the system returns to its initial state.
Correct answer: Zero- A. Exothermic reaction
- B. Endothermic reaction
- C. Spontaneous reaction
- D. Non spontaneous reaction
Explanation: The term exothermic process describes a process or reaction that releases energy from the system to its surroundings, usually in the form…
Correct answer: Exothermic reaction- A. Done by temperature change
- B. Pressure - Temperature Work
- C. Pressure - Volume Work
- D. None of these options is correct
Explanation: The work is pressure-volume work. Pressure-volume work is the work that is done by the compression or expansion of a fluid.
Correct answer: Pressure - Volume Work- A. Joule/mole
- B. kJ/mole
- C. kJ mol
- D. All options are correct.
Explanation: Joule is defined as 1kgm2s-2. Joule is a small quantity of energy, hence chemists usually express it in kJ.
Correct answer: kJ/mole- A. Heat remains constant
- B. Heat is lost
- C. Heat is absorbed
- D. No heat gain or lose takes place
Explanation: Option C is correct since, in an endothermic reaction, the products are higher in energy than the reactants.
Correct answer: Heat is absorbed- A. Enthalpy of Formation
- B. Enthalpy of Neutralization
- C. Enthalpy of Atomization
- D. Enthalpy of Reaction
Explanation: The given reaction ½ H2 → H represents the dissociation of hydrogen molecule into hydrogen atoms, and the enthalpy change associated with…
Correct answer: Enthalpy of Atomization- A. Enthalpy
- B. Internal energy
- C. Thermal energy
- D. Temperature
Explanation: Heat is not a thermodynamic property because heat is the energy that is transferred due to a temperature difference, which means that heat…
Correct answer: Thermal energy- A. Damages ... intolerable
- B. Ambiguities ...superior
- C. Shortcomings ...shoddy
- D. Occurrences ...attractive
Explanation: The sentence can be completed with the following words:"Shortcomings" and "shoddy" So the completed sentence is:"The foreman's clemency…
Correct answer: Shortcomings ...shoddy- A. 2
- B. -1
- C. 5
- D. 4
Explanation: The given sequence is: 2, -1, 2, -1, 2, ?. The pattern here is an alternating one: every second term is the same.
Correct answer: -1- A. If statement I is the cause and statement II is its effect;
- B. If statement II is the cause and statement. I is its effect;
- C. If both the statements I and II are independent causes;
- D. If both the statements I and II are effects of independent causes;
- E. If both the statements I and II are effects of some common cause;
Explanation: Statement II highlights the lack of parks in the locality, which is a plausible reason for the protest described in Statement I.
Correct answer: If statement II is the cause and statement. I is its effect;- A. If only I follows
- B. If only II follows
- C. If either I or II follows
- D. If neither I nor II follows
- E. If both I and II follow
Explanation: The statement indicates that the local government has agreed to provide necessary infrastructural facilities for the trust's clean water…
Correct answer: If both I and II follow