Chemistry · Physics

Thermodynamics and Chemical Kinetics

1,132 Questions

Thermodynamics and chemical kinetics are crucial branches of physical chemistry. This area focuses on energy transformations, reaction rates, equilibrium constants, and catalysts. These topics carry significant weight in competitive science and engineering examinations.

Enthalpy and energyChemical equilibriumEntropy conceptsReaction kinetics and catalysts

Thermodynamics and Chemical Kinetics Questions

Multiple choice

Which of the following statements are FALSE?

  1. The system does work on the surroundings when an ideal gas expands against a constant external pressure.
  2. The change in internal energy, ∆E, for a process is equal to the amount of heat absorbed at constant pressure qp.
  3. If qp for a process is negative, the process is endothermic.
  4. The freezing of water is an example of an exothermic reaction.

  1. 1 and 2

  2. 1 and 4

  3. 2 and 3

  4. 2 and 4

  5. 3 and 4
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yes, it is the correct answer. Both statements 2 and 3 are false. The change in internal energy, ∆E, for a process is equal to the amount of heat absorbed at constant volume qv. The change in enthalpy, ∆H, for a process is equal to the amount of heat absorbed at constant pressure qp. If qp for a process is negative, the process is exothermic.

Multiple choice

A catalyst is a substance which

  1. stops a chemical reaction

  2. helps initiate a reaction

  3. increases the speed of a reaction

  4. decreases the speed of a reaction
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A catalyst is defined as a substance that increases the rate of a chemical reaction without being consumed in the process.

Multiple choice

The process of gradually mixing two gases is called

  1. diffusion

  2. fusion

  3. enthalpy

  4. entropy
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Diffusion is the physical process where particles of different substances intermingle as a result of their spontaneous movement. It is the mechanism by which gases mix.

Multiple choice

For the process K+(g) -----> K(g) - equation 1. K(g) ----->K (s) - equation 2 . Which statement is correct?

  1. Energy is absorbed in 1 and released in 2 .

  2. Energy is relesed in both the processes .

  3. Energy is released in 1 and absorbed in 2 .

  4. Energy is absorbed in both the cases .
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the first equation electron is added to a gaseous anion and energy is released in this process and in the second case also energy is released .

Multiple choice

Which of the following statements is/are false about the internal energy?

  1. The absolute value of internal energy can not be determined.

  2. The internal energy of one mole of a substance is same at any temperature or pressure.

  3. The measurement of heat change during a reaction by bomb calorimeter is equal to the internal energy change.

  4. Internal energy is an extensive property.

  5. The internal energy of a system can be changed by heating the system or by doing work on it.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because the measurement of heat change during a reaction by bomb calorimeter is equal to the internal energy change, and hence this statement incorrect about internal energy.

Multiple choice

Limiting reagent is

  1. the reactant which is present in larger amount

  2. the reagent which is present in lesser amount

  3. the reactant which slows down the speed of reaction

  4. the reagent which is required for completion of the reaction
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ans : 2.

Multiple choice

The function of a catalyst in a reaction is to

  1. decrease the rate of the reaction

  2. increase the rate of the reaction

  3. increase the pressure of the reactants

  4. decrease the pressure of the reactants
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A catalyst is a substance that increases the rate of a chemical reaction by providing an alternative pathway with a lower activation energy. It remains chemically unchanged at the end of the reaction.

Multiple choice

In which reaction is the heat energy absorbed?

  1. Exothermic reaction

  2. Endothermic reaction

  3. Reversible reaction

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An endothermic reaction is a chemical reaction that absorbs heat energy from its surroundings, resulting in a decrease in temperature.

Multiple choice

In chemical change

  1. Molecules of the substance do not change

  2. Molecules of a substance change

  3. Substance remain same

  4. Change is reversible
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Molecules goes under change

Multiple choice

Chemical changes are

  1. Always reversible

  2. Always are irreversible

  3. Mostly irreversible

  4. D. Mostly reversible
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

fact

Multiple choice

In a chemical change

  1. Energy is either absorbed or given out.

  2. Energy is always absorbed

  3. Energy is given out

  4. Energy change do not occur
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

fact