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 chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Choose the correct answer. 

A thermodynamic state function is a quantity : 

  1. used to determine heat chages

  2. whose value is independent of path

  3. used to determine pressure volume work

  4. whose value depends on temperature only
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A thermodynamic state function is a quantity whose value is independent of path. Thus, enthalpy is a state function.
Its value depends on iniital and final states and is independatn of path followed.

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Why are state functions important in chemistry?

  1. They appear a lot in thermochemistry and thermodynamics

  2. Many equations include properties that are state functions

  3. We only need to know the final and initial states

  4. They simplify our calculations

  5. All answers are correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
State functions help us simplify our calculations and see the change in value between the final and starting position, also known as a state change. Mass, pressure, density, energy, temperature, volume, enthalpy, entropy, Gibbs free energy and chemical composition are all examples of state functions in thermochemistry
In simple words, the state functions are important in chemistry as we only need to know the final and initial states.

Hence, the correct option is $C$
Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Which describes an endothermic reaction?

  1. Positive $\displaystyle \Delta H$
  2. Negative $\displaystyle \Delta H$
  3. Positive $\displaystyle \Delta G$
  4. Negative $\displaystyle \Delta G$
  5. Positive $\displaystyle \Delta S$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The term endothermic process describes a process or reaction in which the system absorbs energy from its surroundings so enthalpy change should be positive

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Which of the following statements are correct?

  1. $\Delta H$ is a state function
  2. Value of $\Delta H $ is independent of path taken
  3. $\Delta H$ can be determined under standard condition

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

Change in enthalpy $\triangle H$ is a state function as its value doesn't depend on the path taken i.e. they give a unique value for each given state of a system. Since it gives value independent of path taken, its value at standard condition can be determined(25℃ and 1atm)
Hence all statements are correct.

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Which of the following functions are path independent?

  1. Work

  2. Heat

  3. Gravitational potential energy

  4. Internal energy
Reveal answer Fill a bubble to check yourself
C,D Correct answer
Explanation

In thermodynamics, a state function or function of state is a function defined for a system relating several state variables or state quantities that depends only on the current equilibrium state of the system. State functions do not depend on the path by which the system arrived at its present state. A state function describes the equilibrium state of a system.

For example, internal energy, enthalpy, Gravitational potential energy and entropy are state quantities because they describe quantitatively an equilibrium state of a thermodynamic system, irrespective of how the system arrived in that state.

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

System in which there is no exchange of matter, work or energy from surroundings is:

  1. closed

  2. adiabatic

  3. isolated

  4. isothermal
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Closed System - The system in which only energy can be exchanged with the surrounding.


Adiabatic - The process in which heat is not exchanged by the system with the surroundings, i.e., $Q=0$.


Isolated - The system in which neither energy nor matter can be exchanged with the surroundings.  

Isothermal - The temperature remains constant, i.e., $\Delta T=0$.


Hence, the correct answer is option $\text{C}$.

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Which of the following statement is correct?

  1. The presence of reaction species in a covered beaker is an example of open system.

  2. There is an exchange of energy as well as matter between the system and the surroundings in a closed system.

  3. The presence of reactants in a closed vessel made up of copper is an example of a closed system.

  4. The presence of reactants in a thermos flask or any other closed insulated vessel is an example of a closed system.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In a closed system (For example, the presence of reactants in a closed vessel made of conducting material e.g copper) there is no exchange of matter, but exchange of energy is possible between system and the surroundings.

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Select incorrect statement(s):

  1. A closed system with all adiabatic boundaries must be an isolated system

  2. Total heat exchange in a cyclic process may be zero

  3. Entropy of a closed system is maximum at equilibrium

  4. Molar gibb's Energy is an extensive property
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Since heat is energy, only two systems can stop it from crossing the boundary closed and isolated system. So yes, adiabatic process can happen in an isolated system. But all adiabatic process need not happen in an isolated system, it can happen in a closed system also.
Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Assertion: Heat is not a state function

Reason: The change of heat depends upon the

path followed

  1. both A and R are true and R is the correct explanation of A.

  2. both A and R are true but R is not the correct explanation of A.

  3. A is true but R is false.

  4. both A and R are false.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Heat is a path function. The change of heat depends upon the path followed

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Which of the following statement(s) is/are incorrect?

  1. For a closed system at rest with no fields, the sum of $q+w$ has the same value for every process that goes from a given state 1 to a given state 2
  2. If a closed system at rest in the absence of external field undergoes an adiabatic process that has $w=0$, then the temperature of system must remain constant

  3. A change in state from state 1 to state 2 produces a greater increase in entropy of the sytem when carried out irreversible than when carried out reversibly

  4. The change in entropy of the system for an adiabatic process in a closed system must be zero
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics
Which of the following is not a state function?

  1. Temperature

  2. Density

  3. Work

  4. Volume

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

Temperature, density, volume and pressure are state functions.
They are intrinsic properties of the system. Their values  depend on initial and final state only and are independent of path followed.
On the other hand, work is a path function. It is not an state function. Its value depends on the path followed.