1

Question 1

What is the rate of a chemical reaction?

Answer 1

The speed or rate at which reactants are converted into products in a chemical reaction

It can be affected by factors such as concentration, temperature, pressure, and the presence of a catalyst.

Question 2

What factors can affect the rate of a chemical reaction?

Answer 2

• Concentration
• Temperature
• Pressure
• Presence of a catalyst

These factors can alter the speed at which reactions occur.

Question 3

What is the difference between average and instantaneous rates of reaction?

Answer 3

Average rate is calculated over a time interval, while instantaneous rate is the rate at a specific moment in time

Average rate gives a general speed, while instantaneous rate provides a precise measurement.

Question 4

Give an example of a fast chemical reaction.

Answer 4

Precipitation of silver chloride by mixing aqueous solutions of silver nitrate and sodium chloride

This reaction occurs instantaneously.

Question 5

Give an example of a slow chemical reaction.

Answer 5

Rusting of iron in the presence of air and moisture

This process takes a significant amount of time to occur.

Question 6

What is the mathematical expression for the rate of reaction in terms of concentration?

Answer 6

Rate = Change in concentration of reactant or product per unit time

This can be expressed as the rate of disappearance of reactants or the rate of appearance of products.

Question 7

What do the square brackets in the expressions for concentration represent?

Answer 7

Molar concentration of reactants and products

For example, [R] indicates the concentration of reactant R.

Question 8

In a hypothetical reaction, what does one mole of reactant R produce?

Answer 8

One mole of product P

This is a basic stoichiometric relationship in chemical reactions.

Question 9

Fill in the blank: The rate of disappearance of reactant R is measured as _______.

Answer 9

the change in concentration of R over time

This is crucial for calculating the overall reaction rate.

Question 10

True or False: The rate of a reaction can vary depending on the conditions under which it occurs.

Answer 10

True

Different conditions such as temperature and concentration can significantly alter the reaction rate.

Question 11

What is a collision theory in the context of reaction rates?

Answer 11

A theory that explains how the orientation and energy of molecules during collisions affect the rate of reaction

This theory helps in understanding the mechanisms behind chemical reactions.

Question 12

What is chemical kinetics?

Answer 12

The study of the rates of chemical reactions and the factors affecting them.

Question 13

True or False: The rate of a reaction is constant throughout the reaction.

Answer 13

False

Question 14

What factors affect the rate of a chemical reaction?

Answer 14

Concentration, temperature, surface area, and the presence of catalysts.

Question 15

Fill in the blank: The rate of reaction increases with an increase in ___.

Answer 15

temperature

Question 16

Define ‘reaction rate’.

Answer 16

The change in concentration of a reactant or product per unit time.

Question 17

What is the unit of reaction rate?

Answer 17

mol L^-1 s^-1

Question 18

How does concentration affect the rate of reaction?

Answer 18

Increasing the concentration of reactants generally increases the reaction rate.

Question 19

What is the role of a catalyst in a chemical reaction?

Answer 19

A catalyst increases the rate of a reaction without being consumed in the process.

Question 20

True or False: Catalysts change the equilibrium constant of a reaction.

Answer 20

False

Question 21

What does the rate law expression represent?

Answer 21

The relationship between the rate of a reaction and the concentration of its reactants.

Question 22

What is the general form of a rate law expression?

Answer 22

Rate = k[A]^m[B]^n

Question 23

Define the term ‘order of reaction’.

Answer 23

The sum of the powers of the concentration terms in the rate law.

Question 24

What is zero-order reaction?

Answer 24

A reaction whose rate does not depend on the concentration of reactants.

Question 25

Give an example of a first-order reaction.

Answer 25

Radioactive decay.

Question 26

What is the half-life of a reaction?

Answer 26

The time required for the concentration of a reactant to decrease to half its initial value.

Question 27

True or False: The half-life of a first-order reaction depends on the initial concentration.

Answer 27

False

Question 28

What is an Arrhenius equation?

Answer 28

An equation that shows the relationship between the rate constant and temperature.

Question 29

What is the activation energy?

Answer 29

The minimum energy required for a reaction to occur.

Question 30

Fill in the blank: The rate constant (k) increases with an increase in ___.

Answer 30

temperature

Question 31

What is a reaction mechanism?

Answer 31

The step-by-step sequence of elementary reactions by which overall chemical change occurs.

Question 32

True or False: A slow step in a reaction mechanism is called the rate-determining step.

Answer 32

True

Question 33

Define 'intermediate' in the context of chemical kinetics.

Answer 33

A species that is formed in one step of a reaction mechanism and consumed in another.

Question 34

What is the effect of surface area on the rate of reaction?

Answer 34

Increasing surface area increases the rate of reaction.

Question 35

What type of reaction is characterized by a rate that depends on the concentration of only one reactant?

Answer 35

First-order reaction.

Question 36

What is the significance of the rate constant (k)?

Answer 36

It indicates the speed of the reaction at a given temperature.

Question 37

What is a second-order reaction?

Answer 37

A reaction whose rate depends on the square of the concentration of one reactant or the product of the concentrations of two reactants.

Question 38

Fill in the blank: The rate of a zero-order reaction is independent of the concentration of ___.

Answer 38

reactants

Question 39

What is a complex reaction?

Answer 39

A reaction that involves multiple elementary steps.

Question 40

True or False: The rate of reaction can be affected by the physical state of reactants.

Answer 40

True

Question 41

Define 'homogeneous catalyst'.

Answer 41

A catalyst that is in the same phase as the reactants.

Question 42

What is a heterogeneous catalyst?

Answer 42

A catalyst that is in a different phase from the reactants.

Question 43

What is meant by 'temperature coefficient'?

Answer 43

The factor by which the rate of reaction increases with a 10°C rise in temperature.

Question 44

Fill in the blank: The temperature coefficient for most reactions is approximately ___.

Answer 44

2

Question 45

What does the term 'steady-state approximation' refer to?

Answer 45

An assumption that the concentration of intermediates remains constant during the reaction.

Question 46

What is the effect of pressure on the rate of reaction involving gases?

Answer 46

Increasing pressure increases the rate of reaction by increasing the concentration of gases.

Question 47

True or False: In a first-order reaction, the concentration of reactants decreases exponentially over time.

Answer 47

True

Question 48

What is meant by 'rate constant'?

Answer 48

A proportionality factor in the rate law that is specific to a given reaction at a specified temperature.

Question 49

How does the presence of a catalyst influence the activation energy?

Answer 49

A catalyst lowers the activation energy required for the reaction.

Question 50

Fill in the blank: A reaction that proceeds through a single step is called a ___.

Answer 50

single-step reaction

Question 51

What is the significance of the collision theory?

Answer 51

It explains how chemical reactions occur and why reaction rates differ.

Question 52

What is the role of molecular orientation in a chemical reaction?

Answer 52

Proper orientation of reactant molecules is necessary for effective collisions and reactions to occur.

Question 53

True or False: All collisions between reactant molecules lead to a reaction.

Answer 53

False

Question 54

What is a chain reaction?

Answer 54

A reaction that proceeds through a series of steps, with free radicals generated that propagate the reaction.

Question 55

Define 'transition state'.

Answer 55

A temporary state during a reaction where the reactants are in the process of being converted to products.