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

A reaction A→ B the stoichiometry of both reactant and product are same and hence

  1. the rate of dissappearance of (A) & the rate of appearance of (B) are same.

  2. the rate of appearance of (A) & the rate of appearance of (B) are same.

  3. the rate of appearance of (A) & the rate of dissappearance of (B) are same

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For a reaction A to B with a 1:1 stoichiometry, the rate of disappearance of A equals the rate of appearance of B. The rates of appearance of A and disappearance of B are negative values of the reaction rate.

Multiple choice

Which of these does not influence the rate of reaction?

  1. Nature of the reactants

  2. Concentration of the reactants

  3. Temperature of the reaction

  4. Molecularity of the reaction

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Molecularity is a theoretical concept based on the mechanism of an elementary reaction, whereas rate is influenced by physical conditions like concentration, temperature, and the nature of reactants.

Multiple choice

A reaction involving two different reactants can never be

  1. Unimolecular reaction

  2. First order reaction

  3. Second order reaction

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

A reaction involving two different reactants must involve at least two molecules in the rate-determining step, making it at least bimolecular.

Multiple choice

During the formation of a chemical bond 

  1. Energy decreases

  2. Energy increases

  3. Energy of the system does not change

  4. electron-electron repulsion becomes more than the nucleus-electron attract
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When atoms form a chemical bond, the system moves to a lower energy state to achieve stability, meaning energy is released and the total potential energy decreases.

Multiple choice some important compounds of magnesium and calcium the s-block elements chemistry

Formation of super phosphate is:

  1. exothermic reaction

  2. endothermic reaction

  3. reversible reaction

  4. none of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A well powdered phosphate rock or bone ash mixed known quantity of concentrate sulphuric acid is introduced into a cast iron chamber provided with mechanical stirrer and two valves at bottom. Each valve opens in a big chamber called den. The mixture is stirred for 2 to 5 minutes and then dumped mechanically into one of the dens through the valve. The mass is kept in the den for about 24 hours.

${ Ca } _{ 3 }{ \left( P{ O } _{ 4 } \right)  } _{ 2 }+2{ H } _{ 2 }S{ O } _{ 4 }+4{ H } _{ 2 }O\longrightarrow Ca{ ({ H } _{ 2 }P{ O } _{ 4 }) } _{ 2 }+2CaS{ O } _{ 4 }.2{ H } _{ 2 }O+Heat$

A mixture of calcium sulphate and calcium dihydrogen phosphate is obtained .This mixture is called superphosphate.

Multiple choice chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

When a substance is heated kinetic energy of particles decreases.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Theoretically, heating a solid to higher and higher temperatures changes its phase to a liquid, and finally to a gas.
A solid consists of low kinetic energy vibrating particles locked into position by interparticle attractive forces. When heat is applied, energy is absorbed and the particles start vibrating more vigorously.

Multiple choice chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

Combustion reaction is usually .................. whereas decomposition reaction is ................ usually.

  1. endothermic, exothermic

  2. exothermic, endothermic

  3. endothermic, conduction

  4. none of above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Exothermic reactions release heat and light into their surroundings. For example, combustion reactions are usually exothermic. Endothermic reactions, on the other hand, absorb heat and/or light from their surroundings. For example, decomposition reactions are usually endothermic.

Multiple choice chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

On cooling a gas, potential energy stored is released in the form of:

  1. mechanical energy

  2. kinetic energy

  3. heat energy

  4. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

On cooling a gas, the temperature falls down and the stored potential energy is released in the form of heat energy so that the temperature fall and the gas becomes cool.

Multiple choice chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

According to kinetic theory of gases, molecular kinetic energy increases when:

  1. mixed with other molecules at low temperature.

  2. frozen into solid.

  3. condensed into liquid.

  4. melted from solid to liquid state.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Molecular kinetic energy is maximum in gases and least in solids. Hence, a substance is melted from solid to liquid state, its kinetic energy increases.

Multiple choice physics option b: engineering physics conversion of heat into work: heat engine and it's efficiency engines and cycles refrigerators and heat pumps

A carnot cycle is having maximum efficiency because

  1. it comprises of two adiabatic process which requires no heat in its execution.

  2. it comprises of two isothermal process.

  3. its every process is reversible

  4. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Carnot cycle consists of 4 process. All of them are ideal and practically not possible.

1.Isothermal heat addition- Nothing can be more efficient than this heating since no finite temperature difference exists between heat source and receiver. Hence it is a reversible process and most efficient,

2.Isentropic(reversible adiabatic) expansion- Most efficient expansion, as no heat loss is taking place, full energy is utilised only for expansion and thereby doing work.

3.Isothermal heat rejection- Most efficient heat rejection to a heat sink at same temperature.

4.Isentropic compression- Compressed(without friction) with no heat lost to surrounding. Power input is used only for increasing the pressure and temperature.

In this cycle every process is reversible and hence it is most efficent.
When the cycle is completed input energy and power is used only for the purpose it was intended. Output was completely used for intended purpose
Multiple choice zoology respiratory system of human mechanism of respiration respiratory cycle breathing and exchange of gas

Chloride shift is concerned with the transport of 

  1. $CO _2$ and $O _2$
  2. $N _2$
  3. $CO _2$
  4. $O _2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chloride shift is a process which occurs in a cardiovascular system and refers to the exchange of bicarbonate (HCO$ _{3-}$) and chloride (Cl-) across the membrane of the red blood cells (RBCs).
Therefore, the correct answer is option C.

Multiple choice chemistry energetics and thermochemistry gibbs energy change and equilibrium gibbs free energy entropy and spontaneity

The Van't Hoff equation is :

  1. $\Delta G^{\circ} = RT log _e K _p$
  2. $-\Delta G^{\circ} = RT log _e K _p$
  3. $\Delta G^{\circ} = RT^2 lnK _p$

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

The Van't Hoff equation gives the relationship between the standard gibbs free energy change and the equilibrium constant.  It is represented by the equation $-\Delta  G^{\circ} = RT    log _e   K _p$.