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 30 of 37
- A. HCI(g) ➞ H(g) + Cl(g)
- B. HCL(g) ➞ 1/2 H2(g) + 1/2 - CI2(g)
- C. 2HCI(g) H2(g) + CI2(g)
- D. HCI(g) -H(g) +CI-(g)
Explanation: "The explanation for this question will be added soon!".
Correct answer: HCI(g) ➞ H(g) + Cl(g)- A. (y - 2x)
- B. (x + y)
- C. (2x -y)
- D. 2x/y
Explanation: Reverse the second reaction and change the sign of its enthalpy change: SO3(g) + y kJ → SO2(g) + 1/2 O2(g) Multiply the first reaction by…
Correct answer: (2x -y)- A. Isolated system
- B. Open system
- C. Adiabatic system
- D. Closed system
Explanation: Both energy and mass are transferrable, therefore option B is correct.
Correct answer: Open system- A. 30J
- B. 40 J
- C. 50 J
- D. 20 J
Explanation: To find the increase in internal energy of the system, we can use the first law of thermodynamics, which states: ΔU = Q - W where: ΔU =…
Correct answer: 30J- A. Increased
- B. Decreased
- C. Neither increased nor decreased
- D. First increases and then decreases
Explanation: Option A is correct because the energy of the system during endothermic reactions is increased as it absorbs heat.
Correct answer: Increased- A. Heat capacity
- B. Specific heat
- C. External energy
- D. Internal energy
Explanation: Option D is correct because internal energy includes both kinetic energy, which arises from the random movement of particles, and…
Correct answer: Internal energy- A. Vibrational movements
- B. Translational movements
- C. Rotational movements
- D. All of them
Explanation: Option D is correct as in solid substances, particles are arranged in a fixed lattice, and they vibrate around their equilibrium…
Correct answer: All of them- A. -228.88KJ
- B. -343.52KJ
- C. +228.88kJ
- D. -22.88KJ
Explanation: "The explanation for this question will be added soon!"
Correct answer: -228.88KJ- A. Vibrational movement
- B. Rotational movement
- C. Translational movement
- D. No potential energy
Explanation: Option A is correct because in solid substances, particles are arranged in a fixed lattice, and they vibrate around their equilibrium…
Correct answer: Vibrational movement- A. ∆ E = q w
- B. ∆ E = qv
- C. ∆ E = q + P ∆ V
- D. ∆ E = qp
Explanation: At constant volume no work is done and the entire heat supplied is converted to internal energy ,thus option B is correct.
Correct answer: ∆ E = qv- A. 14
- B. 25
- C. 28
- D. 38
Explanation: One angle of a triangle is 82 °. The other two angles are in the ratio 2:5.
Correct answer: 28- A. When 1 mole of Zn is dissolved in excess HCl, the work done is approximately equal to -2.46 kJ in an open beaker at 300 K and 1 atm.
- B. When 1 mole of Zn is dissolved in excess HCl, the work done is zero in a closed beaker.
- C. Both (a) and (b) are correct.
- D. Neither (a) nor (b) are correct.
Explanation: The correct answer is Option C: Both (a) and (b) are correct. In an open beaker, when zinc reacts with hydrochloric acid, work is done as…
Correct answer: Both (a) and (b) are correct.- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: The correct answer is Option A because it correctly calculates the specific heat at constant pressure per gram of gas using the given…
Correct answer: Option A- A. ΔHf = x1+ 3x2 - 6x3
- B. ΔHf = 3x3 - 1/2x1 - 3/2 x2
- C. ΔHf = x1/2 + 3/2x2 - 3x3
- D. ΔHf = 6x3 - x1 - 3x2
Explanation: To find the enthalpy of formation (ΔHf) of NH3, consider the bond dissociation energies: The formation of NH3 from N2 and H2 involves…
Correct answer: ΔHf = x1/2 + 3/2x2 - 3x3- A. 100 mol
- B. 10 mol
- C. 20 mol
- D. 200 mol
Explanation: The formation of glucose from CO2 and H2O in plant cells is a non-spontaneous process with a Gibbs free energy change of 3000 kJ/mol…
Correct answer: 100 mol- A. 0.75 atm
- B. 2 atm
- C. 2.5 atm
- D. 0.5 atm
Explanation: In an adiabatic process for an ideal monoatomic gas, the relationship between pressure and temperature is given by the equation…
Correct answer: 0.75 atm- A. Energy can neither be created nor destroyed
- B. One form of energy can be converted into another form of energy
- C. In an adiabatic process, the work done is independent of its path
- D. Continuous production of mechanical work without supplying an equivalent amount of heat is possible
Explanation: The first law of thermodynamics, or the law of conservation of energy, states that energy cannot be created or destroyed, only transformed…
Correct answer: Continuous production of mechanical work without supplying an equivalent amount of heat is possible- A. Heat lost by the system
- B. Work done on the system
- C. Work done by the system
- D. Positive ∆E when heat is lost by the system
Explanation: OPTION A: Heat lost by the system is considered to have a negative value in thermodynamics.
Correct answer: Work done on the system- A. Internal energy
- B. Volume
- C. Work
- D. Enthalpy
Explanation: The correct answer is Option C: Work. Work is not a state function because it depends on the specific process or path taken to change the…
Correct answer: Work- A. 40 kJ
- B. 10 kJ
- C. 20 kJ
- D. 0 kJ
Explanation: In thermochemistry, when a process occurs at constant volume, no work is done on or by the system because work is defined as W = -PΔV…
Correct answer: 0 kJ