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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- A. endothermic
- B. spontaneous
- C. non-spontaneous
- D. exothermic
Explanation: If the reactants have greater enthalpy than the products, ΔH = Hproducts - Hreactants is negative, so heat is released and the reaction is…
Correct answer: exothermic- A. endothermic
- B. spontaneous
- C. non-spontaneous
- D. exothermic
Explanation: A reaction that evolves or releases heat to its surroundings has a negative enthalpy change and is called exothermic.
Correct answer: exothermic- A. endothermic
- B. exothermic
- C. unpredictable
- D. same
Explanation: In an exothermic reaction, chemical energy is released to the surroundings, so the reactants have greater enthalpy than the products.
Correct answer: exothermic- A. pressure and temperature
- B. pressure and volume
- C. heat and volume
- D. heat and work
Explanation: Heat and work are the two ways energy crosses the boundary of a thermodynamic system, and both are measured in joules (J).
Correct answer: heat and work- A. pressure and temperature
- B. pressure and volume
- C. heat and work
- D. heat and volume
Explanation: Energy crosses the boundary of a thermodynamic system mainly as heat or work, expressed in the first law as ΔU = q + w.
Correct answer: heat and work- A. calculated by Hess law
- B. can be measured by calorimeter
- C. both A and B
- D. none
Explanation: An enthalpy change can be obtained experimentally from heat measurements in a calorimeter or calculated indirectly using Hess's law by…
Correct answer: both A and B47. The second nuclear weapons used in warfare over Nagasaki, Japan, contain energy equal about of TNT?
- A. 1.5 kilotons
- B. 20 kilotons
- C. 25 kilotons
- D. 30 kilotons
Explanation: The Nagasaki plutonium bomb, Fat Man, had an estimated explosive yield of about 21 kilotons of TNT, which is conventionally rounded to…
Correct answer: 20 kilotons- A. Change in state of the system is increased
- B. Temperature of the ystem may rise
- C. Chemical reaction may take place
- D. All
Explanation: An increase in internal energy can appear as a temperature rise, a change of physical state, or energy that enables a chemical reaction…
Correct answer: All- A. No heat enter or leave the system
- B. Pressure of the system remains constant
- C. temperature of the system remains constant
- D. Volume of the system remains unchanged
Explanation: An isothermal process is defined by constant temperature, so the temperature of the system remains unchanged.
Correct answer: temperature of the system remains constant- A. Open system
- B. closed system
- C. Isolated system
- D. All of the above
Explanation: A closed system can exchange energy, such as heat or work, with its surroundings but does not exchange matter.
Correct answer: closed system- A. Extensive properties
- B. Colligative properties
- C. intensive properties
- D. None of These
Explanation: An intensive property does not depend on the amount or mass of a substance, for example temperature, pressure and density.
Correct answer: intensive properties- A. Einstein
- B. Dr.A.Walash
- C. Schwartz
- D. S.E.Manhan
Explanation: Schwartz is credited in this question with using the term concentration window for drawing arbitrary concentration limits or lines of…
Correct answer: Schwartz- A. Boltzmann
- B. Gibbs
- C. Carnot
- D. Mexwell
Explanation: The ensemble concept in statistical thermodynamics was introduced by J. Willard Gibbs.
Correct answer: Gibbs- A. 6 feet
- B. 6 meters
- C. 60 feet
- D. 100 cm
Explanation: A fathom is a traditional unit of length used especially for depth in water.
Correct answer: 6 feet- A. specific heat
- B. thermal capacity
- C. water equivalent
- D. None of the above
Explanation: The heat required to raise the temperature of an entire body by 1 K is its heat capacity, also called thermal capacity, with units J K^-1.
Correct answer: thermal capacity- A. Electrchemistry
- B. Matrix mechanics
- C. Statistical thermodynamics
- D. Soectroscopic analysis
Explanation: Statistical thermodynamics connects microscopic quantum states and molecular energy distributions with macroscopic thermodynamic…
Correct answer: Statistical thermodynamics57. Every sample of matter with uniform properties and fixed composition is called_________________?
- A. solute
- B. solvent
- C. solution
- D. phase
Explanation: A phase is a homogeneous part of matter with uniform physical and chemical properties and a definite composition.
Correct answer: phase- A. J
- B. KCaL
- C. Cal
- D. GJ
Explanation: The SI unit of heat is the joule, written J, because heat is a form of energy and the SI unit of energy is the joule.
Correct answer: J- A. path of reaction
- B. initial state
- C. final state
- D. initial and final state
Explanation: A state function has a value determined only by the initial and final states, not by the route taken between them.
Correct answer: initial and final state- A. system
- B. surrounding
- C. phase
- D. state functions
Explanation: Thermodynamic parameters such as pressure, temperature, volume, internal energy and enthalpy are generally state functions, with values…
Correct answer: state functions