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 botany ecosystem : structure and function energy flow in food chain food chain and energy flow energy flow in ecosystem

According to first law, energy cannot be created nor destroyed, but, can only show a state known as

  1. Utilized

  2. Thermodynamics

  3. Convection

  4. Conversion
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The first law of thermodynamics states that energy is conserved; it can be converted from one form to another but cannot be created or destroyed. The process of changing energy from one form to another is called conversion.

Multiple choice botany ecosystem : structure and function energy flow in food chain food chain and energy flow energy flow in ecosystem

Choose the correct answers from the alternatives given .
Which of the following statements is not a consequence of the second law of thermodynamics?

  1. While the total amount of energy is unchanged, the energy lost as heat is no longer useful to the cell in doing work

  2. Reactions that occur spontaneously are those that increase the amount of useful energy in a system

  3. Amount of disorder in the universe is always increasing

  4. To maintain rganisation of a cell, a continual input of energy is required
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In spontaneous reactions release free energy and it moves to a lower, more thermodynamically stable energy state. Hence, instead of an increase in the amount of useful energy in a system spontaneous reactions release free energy. 

So, the correct option is 'Reactions that occur spontaneously are those that increase the amount of useful energy in a system'.

Multiple choice botany ecosystem : structure and function energy flow in food chain food chain and energy flow energy flow in ecosystem

Choose the correct answers from the alternatives given .
Which of the following best describes the second law of thermodynamics?

  1. Energy is neither created nor destroyed, but it can change from one energy form to another

  2. Energy can be created from matter or used to produce mailer

  3. Some useful energy is lost as heat whenever an energy transfer occurs

  4. Energy transfers are always 100% efficient in changing energy from one useful form to another
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The second law of thermodynamics states that whenever energy is transformed, there is a loss of energy through the release of heat. This occurs when energy is transferred between trophic levels as illustrated in a food web. When one animal feeds off another, there is a loss of heat (energy) in the process. Additional loss of energy occurs during respiration and movement. Hence, more and more energy is lost as one moves up through trophic levels.
So, the correct option is 'Some useful energy is lost as heat whenever an energy transfer occurs'.
Multiple choice botany ecosystem : structure and function energy flow in food chain food chain and energy flow energy flow in ecosystem

Choose the correct answers from the alternatives given .
According to the first law of thermodynamics

  1. systems rich in energy are intrinsically unstable

  2. all processes increase the entropy of the universe

  3. energy is conserved in all processes

  4. matter can be neither created nor destroyed
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The First Law of Thermodynamics states that heat is a form of energy, and thermodynamic processes are therefore subject to the principle of conservation of energy. This means that heat energy cannot be created or destroyed.

So, the correct option is 'energy is conserved in all processes'.

Multiple choice botany ecosystem : structure and function energy flow in food chain food chain and energy flow energy flow in ecosystem

Choose the correct answers from the alternatives given .
Which of the following describes the first law of thermodynamics?

  1. Energy is neither created nor destroyed, but it can change into matter

  2. Energy is neither created nor destroyed, but it can change from one energy form to another

  3. Some useful energy is lost as heat whenever an energy transfer occurs

  4. Energy transfers are always 100% efficient in changing energy from one useful form to another
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The first law of thermodynamics says that energy can't be created or destroyed, but it can be changed. The law forms the basis of the principle of conservation of energy. This means that anything that uses energy is changing the energy from one kind of energy to another.

So, the correct option is 'Energy is neither created nor destroyed, but it can change from one energy form to another'.

Multiple choice botany ecosystem : structure and function energy flow in food chain food chain and energy flow energy flow in ecosystem

Which law states that, conversion of energy from one form to another is not 100% efficient?

  1. First law of thermodynamics

  2. Second law of thermodynamics

  3. Energy flow

  4. Biological system
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The second law of thermodynamics states that energy transfers are never 100% efficient, as some energy is always lost as heat during the conversion process.

Multiple choice botany organisms and their environment energy flow in food chain food chain and energy flow energy flow in ecosystem

Choose the correct answers from the alternatives given .
Endergonic reactions

  1. are always coupling reactions

  2. can only occur if there is an input of energy

  3. have products with less free energy than the reactants

  4. all of the above are correct
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Endergonic needs an input of energy to create the products, which have more free energy as a whole than the sum of free energy of each of the reactants. An example of this type of reaction in biology is photosynthesis. This process depends on the reaction to absorb energy in the form of sunshine from the surroundings for it to occur. 
So, the correct option is 'can only occur if there is an input of energy'. 

Multiple choice botany organisms and their environment energy flow in food chain food chain and energy flow energy flow in ecosystem

Choose the correct answers from the alternatives given .
A living organism represents stored energy in the form of chemical compounds When an organism dies, what happens to.that stored energy?

  1. All chemicals immediately lose their high-energy bonds

  2. All molecules immediately degrade into basic elements

  3. All energy immediately leaves, and that is. one manifestation that the organism is dead

  4. Chemical compounds in cells lose their organisation over time because there is no longer an input of energy to maintain the organised state
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

There is constant input of energy needed for all the activities that go inside a living organism. Food is the source of this energy. When an organism dies, these activities or reactions are stopped which results in loss of organisation of chemical compounds in cells. 

So, the correct option is 'Chemical compounds in cells lose their organisation over time because there is no longer an input of energy to maintain the organised state'.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

Law of constant composition is also called as the law of :

  1. Conservation of mass

  2. Conservation of energy

  3. Multiple proportion

  4. Definite proportion
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Law of constant composition is also called as the law of Definite proportion which says that the law of constant composition is a chemistry law which states samples of a pure compound always contain the same elements in the same mass proportion.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

In a compound the ratio of the atoms or element by mass remains always same irrespective of :

  1. temperature

  2. nature of compound

  3. source of compound

  4. size of compound
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Compounds are formed by the combination of two or more elements. In a compound the ratio of the atoms or element by mass remains always same irrespective of the source of compound. This means a certain compound always formed by the combination of atoms in same ratio by mass. If the ratio of mass of constituent atoms will be altered the new compound is formed.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

If the ratio of the atoms by mass is altered then :

  1. new compound formed

  2. same compound are formed

  3. no reaction takes place

  4. state of compound are changed
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a compound the ratio of the atoms or element by mass remains always same irrespective of the source of compound. This means a certain compound always formed by the combination of atoms in same ratio by mass. If the ratio of mass of constituent atoms will be altered the new compound is formed.

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Which of these are spontaneous at higher temperature?

I : $2CuS\, +\, C\, \rightarrow\, 2Cu\, +\, CS _2$ 

II : $ 2CaS\, +\, C\, \rightarrow\, 2Ca\, +\, CS _2$ 

III : $ 2CuS\, +\, 3O _2\, \rightarrow\, 2CuO\, +\, 2SO _2$

Given that : $\Delta\,G^{\circ} _f$ (in $kJ$.$mol^{-1}$) for $CuS\, =\, -49$; $CS _2\, =\, 63.6$ ;  $CaS\, =\, -1320$; $CuO\, =\, -127.2$ and $SO _2\, =\, -300.4$ 

  1. $2CuS\, +\, C\, \rightarrow\, 2Cu\, +\, CS _2$
  2. $ 2CaS\, +\, C\, \rightarrow\, 2Ca\, +\, CS _2$
  3. $ 2CuS\, +\, 3O _2\, \rightarrow\, 2CuO\, +\, 2SO _2$

  4. None of these
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Multiple choice enzymes and catalysts catalysis adsorption and colloids surface chemistry chemistry adsorption theory of heterogeneous catalysis

What does a catalyst do?

  1. Alter the state of equilibrium.

  2. Decreases the activation energy.

  3. Increases collision frequency.

  4. Increases the average kinetic energy of reacting species.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Catalyst is a substance, which lowers the activation energy of reaction because it provides an alternate pathway for reaction. Also, it increases backward and forward reaction to the same extent. Due to this lower activation energy, equilibrium is attained faster.

Multiple choice enzymes and catalysts catalysis adsorption and colloids surface chemistry chemistry adsorption theory of heterogeneous catalysis

Which of the following is the best way to speed up a chemical reaction?

  1. Make an effort to concentrate the reactants as best as possible

  2. Add a catalyst

  3. Cool the reaction down

  4. Increase the pressure on the system
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
5 ways to increase the reaction rate :
1. The nature of the reactants: A reaction between two gases would be faster than a reaction between to liquids or two solids.
2. Temperature:  The heat causes the particles to move quickly, and due to the Collision Theory,  the reaction will occur faster.
3. Concentration: The higher the concentration of a reactant, the quicker the reaction will occur. 
4. Surface Area: The more the particles are exposed, the faster it is for the other reactant to collide into the particles, meaning the reaction rate will increase.
5. Catalysts: Catalysts are substances that increase the rate of reaction by speeding up the reaction without being used up in the reaction.
Adding catalyst can most effectively speed up the chemical reaction. 
Multiple choice enzymes and catalysts catalysis adsorption and colloids surface chemistry chemistry adsorption theory of heterogeneous catalysis

A catalyst increases the rate of a reaction by:

  1. increasing the activation energy of the reaction
  2. increasing the value of rate constants $(k _f$ and $k _b)$

  3. increasing the enthalpy change of the reaction

  4. decreasing the enthalpy change of the reaction
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A catalyst increases rate of reacting by decreasing activation energy. and increasing the enthalpy change of the reaction