Chemistry · Physics

Thermodynamics and Chemical Kinetics

1,092 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 is/are false?

a. At a receptor, the energy provided by a stimulus sets off a chemical reaction which converts the energy of stimulus into electrical impulse. b. Animals react to stimuli in many different ways because they have a nervous system but no endocrine system involving hormones. c. Amoeba tend to aggregate in moderately warm water which is their stimuli to heat.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is the correct option as this statement is false. Animals react to stimuli in many different ways because they have a nervous system and an endocrine system involving hormones.

Multiple choice

Which of the following statements describes an endothermic change?

  1. Changes in which heat is liberated.

  2. Changes which take place in few seconds.

  3. Changes which take days, months, and years to occur.

  4. Changes in which energy is absorbed.

  5. Changes which occur at fixed interval of time.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It is an endothermic change.

Multiple choice

For the reaction- 2SO2 (g) SO3 (g) ⇌ 2SO3 + Heat the yield of SO3 will be maximum if-

  1. The temperature is increased and pressure is kept constant

  2. The temperature is decreased and pressure is increased

  3. Both the temperature and the pressure proteins are increased

  4. Both the temperature and the pressure are decreased
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to Le Chatelier's principle, for an exothermic reaction where heat is released on the product side, decreasing the temperature shifts the equilibrium forward to produce more heat. Furthermore, increasing pressure favors the side with fewer moles of gas (reactants have 3 moles, products have 2 moles), thus maximizing the yield of SO3.

Multiple choice

Which one of the following is true for the flow of water from level to low level (at constant temperature an pressure)?

  1. ∆ G = 0

  2. ∆ G = 1

  3. ∆ G < 0

  4. ∆ G = ∞
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In thermodynamics, a spontaneous process (like water flowing from a high level to a low level) occurs when there is a decrease in the Gibbs Free Energy of the system. Therefore, for such a process at constant temperature and pressure, the change in Gibbs Free Energy (delta G) must be less than zero (negative). If delta G were zero, the system would be at equilibrium.

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, without being consumed in the process.

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

Which of the following pairs is liquid and shows negative deviation?

  1. Benzene and chloroform

  2. Benzene and toluene

  3. Acetone and benzene

  4. Chlorobenzene and bromobenzene

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct because certain solutions have lowest vapour pressure and maximum boiling point. Such a solution is formed by decreasing the volume and evolution of heat. Both the solutions have negative deviation.

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.