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 29 of 37
- A. q= ∆E+W
- B. ∆E q-w
- C. ∆E = q+w
- D. ∆H = ∆E + P∆V
Explanation: The correct depiction of enthalpy is ∆H = ∆E + P∆V.
Correct answer: ∆H = ∆E + P∆V- A. ∆H = O
- B. ∆H > ∆E
- C. ∆H = ∆E
- D. ∆H < ∆E
Explanation: In summary, the correct statement is "c) ∆H = ∆E" because, for this reaction, the change in enthalpy (∆H) is equal to the change in…
Correct answer: ∆H = ∆E563. If work done on a system is 650) and heat taken out from the system is 500J, the change in internal?
- A. -1150
- B. +1150
- C. +150
- D. -150
Explanation: The change in internal energy is given by the equation:∆E = q - w,where q is the heat transferred to the system and w is the work done by…
Correct answer: +150- A. Potential energy
- B. Kinetic energy
- C. Electric energy
- D. Heat energy
Explanation: The energy possessed by water in a dam is potential energy.Potential energy is the energy that an object has due to its position or state.
Correct answer: Potential energy- A. Reversible
- B. Mechanical
- C. Exothermic
- D. Endothermic
Explanation: The process is endothermic.Endothermic processes are those in which heat is absorbed from the surrounding.
Correct answer: Endothermic- A. It is an exothermic process
- B. Formation of water is a spontaneous process
- C. It is the heat evolved for complete reaction of 2 moles of oxygen with excess of hydrogen
- D. Water is at lower energy than its reactants
Explanation: The enthalpy change (∆H) is negative, which means that heat is absorbed from the surroundings during the formation of water.
Correct answer: It is an exothermic process- A. For liquids
- B. for solids
- C. for Any in gas phase rex
- D. For gas phase rex. having greater no. of moles of product.
Explanation: The answer is for gas phase reactions having greater number of moles of products.The enthalpy change (∆H) and the internal energy change…
Correct answer: For gas phase rex. having greater no. of moles of product.- A. q1 + q2
- B. q1 - q2
- C. q2 - q1
- D. -q1 - q2
Explanation: The enthalpy change for the reaction CH3COOH → CH3COO- + H is the difference between the enthalpy change for the first reaction and the…
Correct answer: q1 - q2- A. lonization energy
- B. Electron affinity
- C. Combustion
- D. Exothermic reaction
Explanation: The answer is ionization energy.Ionization energy is the energy required to remove an electron from an atom or molecule in the gaseous…
Correct answer: lonization energy- A. H2 + l2 ➞ 2HI
- B. 2H2O2➞2H2O+O2
- C. PCI5 ➞ PCI3+Cl2
- D. C+O2 ➞ CO2
Explanation: The change in enthalpy is equal to the change in internal energy for reaction 1, H2 + I2 ➞ 2HI as ∆ n = 0
Correct answer: H2 + l2 ➞ 2HI- A. The change in heat content
- B. The total energy change at constant pressure and temperature
- C. The heat change at constant volume if ∆n=0
- D. Work done at constant pressure
Explanation: The change in enthalpy is defined as the total energy change at constant pressure and temperature.
Correct answer: The total energy change at constant pressure and temperature- A. Thermochemistry
- B. Electrochemistry
- C. Nuclear chemistry
- D. Chemical kinetics
Explanation: The study of heat changes that accompany a chemical reaction is called "Thermochemistry", therefore option A is the correct answer.
Correct answer: Thermochemistry- A. It indicates physical state of reactants and products
- B. It indicates whether the reaction is exothermic or endothermic
- C. It indicates allotropes of the reactants if present
- D. It indicates whether a reaction would occur or not
Explanation: The indication of whether a reaction would occur or not is not a characteristic of a thermochemical equation.Thermochemical equations only…
Correct answer: It indicates whether a reaction would occur or not- A. The heat liberated during the neutralization of a strong acid and a strong base in aqueous solution is constant
- B. The heat of combustion is always an exothermic change
- C. The enthalpies of the formation of carbon dioxide can be conveniently determined if the heat of combustion data of carbon is given
- D. The heat of formation of a compound is equal in magnitude to the heat of combustion
Explanation: The statement is not true. The heat of formation and the heat of combustion are two different thermodynamicquantities related to chemical…
Correct answer: The heat of formation of a compound is equal in magnitude to the heat of combustion- A. Graphite is chemically different from diamond
- B. Graphite is as stable as diamond
- C. Graphite is more stable than diamond
- D. Diamond is more stable than graphite
Explanation: The negative value of ∆H (-1.9 kJ) for the transition of carbon from diamond to graphite indicates that the process is exothermic and that…
Correct answer: Graphite is more stable than diamond- A. decreases
- B. remains constant
- C. increases
- D. None of the above
Explanation: Option A is correct because the solution temperature would decrease as there would be more substances absorbing the heat.
Correct answer: decreases- A. Joule
- B. Kelvin
- C. Calorie
- D. Kilo joule (KJ)
Explanation: Option B is correct because Kelvin is the unit that only measures temperature.
Correct answer: Kelvin- A. Universe
- B. Boundary
- C. System
- D. Surrounding
Explanation: Option C is correct because anything that is under observation is called a system because whatever is in it is carefully observed and…
Correct answer: System- A. 163.32 kj/mol
- B. 32.64 kj/mol
- C. 326.4 KJ/mol
- D. 3.264 kJ/mol
Explanation: To calculate the energy evolved when 7.8 g of benzene (C6H6) is burnt in air, we need to use the given enthalpy change (∆H) and the molar…
Correct answer: 326.4 KJ/mol- A. Conditions of P or V under which a reaction is carried out
- B. Initial and final enthalpies of the reactants and products
- C. State of reactants and products
- D. Number of intermediate stages involved
Explanation: Option D is correct because enthalpy is a state function. So, enthalpy change does not depend upon the different steps involved in the…
Correct answer: Number of intermediate stages involved