Chapter 8 Extent of chemical reactions

Question 1

Actual yield

Answer 1

The mass of product actually obtained in the chemical reaction. This will be less than or equal to the theoretical yield.

Question 2

Closed system

Answer 2

A system which allows only energy to be exchanged with the surroundings.

Question 3

Competing equilibria

Answer 3

Equilibria which have a common reactant; each equilibrium system can be regarded as competing for the reactant. The equilibrium system with the larger equilibrium constant has a significant effect on the position of equilibrium of the other reaction.

Question 4

Dynamic equilibrium

Answer 4

A point in a chemical reaction at which the rate of the forward reaction is equal to the rate of the reverse reaction.

Question 5

Open system

Answer 5

A system which allows matter and energy to be exchanged with the surroundings.

Question 6

Equilibrium

Answer 6

In a chemical reaction system, equilibrium is reached when the quantities of reactants and products remain unchanged. The rates of the forward and reverse reactions are equal.

Question 7

Equilibrium constant Kc

Answer 7

The value of the concentration fraction when equilibrium is reached, symbol Kc.

Question 8

Equilibrium law

Answer 8

The equilibrium law as defined for a reversible reaction.

Question 9

Equilibrium yield

Answer 9

The amount of product obtained when a chemical reaction reaches equilibrium

Question 10

Extent of reaction

Answer 10

The relative amounts of products compared to reactants. The extent of the reaction is indicated by the value of the equilibrium constant

Question 11

Heterogenous reactions

Answer 11

A chemical reaction in which at least two of the species are in a different state or phase

Question 12

Homogenous reactions

Answer 12

A chemical reaction in which all the species are in the same state or phase

Question 13

Irreversible reaction

Answer 13

A reaction in which significant reaction can occur in one direction only

Question 14

Partial pressure

Answer 14

The pressure exerted by one component of a mixture of gases. The total pressure of a mixture of gases is equal to the sum of the individual partial pressures of each component in the mixture

Question 15

Percentage yield

Answer 15

Percentage yield=(actual yield)/(theoretical yield)*100

Question 16

Position of equilibrium

Answer 16

The relative amounts of reactants and products at equilibrium. The position of equilibrium varies depending on the extent of the reaction.

Question 17

Rate of reaction

Answer 17

The change in concentration of a reactant or product per unit of time (usually one second).
Rate of reaction = (Change in Concentration)/Time

Question 18

Reaction Quotient Qc/Concentration fraction

Answer 18

The ratio of concentration of products to reactants in a reversible reaction, as expressed in the equilibrium law.

Question 19

Reversible reaction

Answer 19

A reaction in which significant reaction can occur in the reverse reaction as well as the forward direction. Products are present and can react with each other under suitable conditions.

Question 20

Surroundings

Answer 20

The rest of the universe around a particular chemical reaction. The chemical reaction is the system. Energy moves between the system and the surroundings in endothermic and exothermic reactions.

Question 21

System

Answer 21

In Chemistry, a system is a chemical reaction. A system operates within its surroundings. Energy moves between the two. You always consider energy as being absorbed or released from the perspective of the system. For example, energy is absorbed into the system from the surroundings, or energy is released by the system to the surroundings.

Question 22

Theoretical yield

Answer 22

The mass that is expected for a particular product in a chemical reaction, based on the mass of limiting reactant used.