Free Thermochemistry and Energetics of Chemical Reactions MCQs with Answers

• A. Electron affinity
• B. Lattice energy
• C. Crystal energy
• D. All of the above

Explanation: As we know that the electron affinity can be calculated by using Born Haber cycle.

• A. The reaction proceeds in the forward direction at 300 K
• B. At 1200 K, reaction proceeds in the reverse direction
• C. At 300 K, Kp > 1
• D. At 300 K, the products will be favoured more than reactants at equilibrium

Explanation: is incorrect. As in an exothermic reaction, when temperature is decreased reaction shifts towards product side and thus Kp <1 .

• A. The thermodynamics first law is not sufficient to predict the direction of the process
• B. In the case of an exothermic reaction, the overall enthalpy of the products is greater than that of reactants
• C. For the reaction H2(g) + Br2(l) → 2HBr (g) from the bond enthaly data, It is possible to calculate the value of H
• D. At 298K and 1 atmpressure, diamond's standard enthalpy is zero

Explanation: The first law of thermodynamics, which states that energy cannot be created or destroyed, but can be converted from one form to another…

• A. ΔH is positive for exothermic reaction
• B. ΔH is negative for endothermic reactions
• C. The heat of neutralization of strong acid with strong base is always the same
• D. The enthalpy of fusion is negative

Explanation: Enthalpy of neutralization is merely the heat of formation of liquid water from its ionic components.

• A. ΔHf
• B. ΔHc
• C. ΔHsol
• D. Both A and C

Explanation: ΔHf may be +ve or-veΔHsol may be +ve or-veΔHc = always-veΔHat= always +ve

• A. ΔH=ΔE+PΔV
• B. ΔH=ΔE-ΔnRT
• C. ΔE=ΔH+ΔP
• D. ΔH=ΔE-PΔV

Explanation: The enthalpy changes of a process is given by following relation: ΔH=ΔE+PΔV

• A. 273 K
• B. 373K
• C. 298K
• D. 473K

Explanation: Standard conditions for enthalpy measurement are given below:Temperature=25°C (298 K), Pressure= 1 atm

• A. ∆H° of the reaction depends on temperature
• B. ∆H° of reaction can be > or < zero
• C. ∆H° of catalyzed and uncatalyzed reaction is same
• D. ∆H° is always < 0

Explanation: For endothermic reactions, ∆H° is greater than 0. Hence option D is false and is the correct answer.

• A. Spontaneous reaction
• B. Rate of reaction
• C. Heat of reaction
• D. Entropy of reaction

Explanation: The branch of thermodynamics does not directly deal with the rate of reaction. Hence, B is the correct option.

• A. E
• B. G
• C. H
• D. q

Explanation: Option D, q (heat), is correct because it is not a state function.A state function is a property that depends only on the current state of…

• A. A
• B. B
• C. C
• D. D

Explanation: Option C has been identified as the incorrect statement about enthalpy changes (∆H°).

• A. Force
• B. Work
• C. Power
• D. Velocity

Explanation: The erg is a unit of energy and work in the CGS system. One erg is equal to one dyne applied over a distance of one centimeter.

• A. Initial condition of the system
• B. Final condition of the system
• C. Path of the system
• D. Both initial and final condition of the system

Explanation: State functions provide valuable information about the thermodynamic state of a system, and they are used to describe and predict the…

• A. In bond breaking
• B. In endothermic reactions
• C. In bond formation
• D. Both A and B

Explanation: The correct answer is "Both A and B." Both bond breaking and endothermic reactions involve the absorption of energy from the surroundings.

• A. Chemical equilibrium
• B. Chemical bonding
• C. Heat contents of a compound
• D. All of these

Explanation: Thermochemistry provides information about the heat contents of compounds, especially in the context of chemical reactions.

• A. Avogadro's law
• B. Gas laws
• C. Hess's law
• D. Faraday's law

Explanation: There are many compounds, for which ∆H cannot be measured directly by calorimetric method.

• A. Thermochemistry is the study of relation between heat energy and chemical reactions
• B. An exothermic reaction is one which is accompanied by evolution of heat
• C. An endothermic reaction is one in which heat is absorbed
• D. Energy needed to raise the temperature of substance by 1°C is specific heat.

Explanation: The false statement is Energy needed to raise the temperature of a substance by 1°C is specific heat.

• A. Initial and final enthalpy change of reaction
• B. Different intermediate reactions
• C. State of reactants and products
• D. Nature of reactants and products

Explanation: Option B is correct because enthalpy is a state function. So, enthalpy change does not depend upon the different steps involved in the…

• A. Heat energy
• B. Heat of hydration
• C. Lattice energy
• D. Heat of solution

Explanation: The Born-Haber cycle is a theoretical model that allows us to calculate the lattice energy of ionic compounds.

• A. It is an endothermic process
• B. It can be represented as H3O+(aq)+ OH-(aq) → 2H2O(l)
• C. The enthalpy change per mole of H2O formed is independent of the acid or alkali used as they are strong
• D. Both B and C

Explanation: The correct answer is C. The standard enthalpy change of neutralization is approximately -57.4 kJmol-1 for the reaction of strong acids…