Rates and Equilibrium

Question 1

Activation Energy

Answer 1

Minimum amount of energy required for a reaction to take place.

Question 2

Rate of reaction

Answer 2

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

Question 3

Temperature

Answer 3

A measure of kinetic energy of the particles of a substance

Question 4

Catalyst

Answer 4

A substance which speeds up the rate of reaction by lowering the activation energy, remaining unchanged by the reaction

Question 5

Average Rate of Reaction

Answer 5

The change in concentration of a reactant or product per unit time, as measured over a certain time period.

Question 6

Formulae to calculate average rate of reaction

Answer 6

(change in quantity) / (change in time)

Question 7

Maxwell-Boltzmann Distribution

Answer 7

A graph showing the distribution of energy across a sample of particles

Question 8

Reversible Reaction

Answer 8

A chemical reaction that can occur in either the forward or reverse direction, given appropriate conditions

Question 9

Closed System

Answer 9

A system in which no substances can escape or be added

Question 10

Dynamic Equilibrium

Answer 10

A situation in which the rate of the forward and reverse reactions are equal, resulting in no observable change over time.

Question 11

Yield

Answer 11

The amount of product produced

Question 12

Position of equilibrium

Answer 12

An evaluation of the relative amount of products compared to reactants.

Question 13

At equilibrium, if more products are present, equilibrium is said to be on the…

Answer 13

Right

Question 14

At equilibrium, if more reactants are present, equilibrium is said to be on the…

Answer 14

Left

Question 15

Le Chatelier’s Principle

Answer 15

A system at equilibrium has a tendency to partially oppose a disruption

Question 16

What is collision theory

Answer 16

In order for a reaction to occur, particles must collide with the correct orientation and sufficient energy to disrupt the bonds in their molecules.

Question 17

How can the rate of a reaction be altered?

Answer 17

• change the surface area of a solid reactant
• change the temperature
• change the concentration of a solution
• change pressure of gases
• using a catalyst

Question 18

Explain how increasing the surface area of a solid increases rate of reaction

Answer 18

Increasing surface area, increases the frequency of successful collisions between reactant particles per unit time

Question 19

Explain how increasing the concentration of a reactant increases rate of reaction

Answer 19

Increasing concentration increases the frequency of successful collisions between reactant particles per unit time

Question 20

Explain how decreasing volume, to increase pressure, increases the rate of a reaction between gas molecules.

Answer 20

Increasing pressure of a gaseous system increases the frequency of successful collisions between reactant particles per unit time

Question 21

Explain how increasing temperature increases the rate of reaction

Answer 21

Increasing temperature increases the kinetic energy of the particles, increasing the proportion of particles with energy equal to or greater than the activation energy therefore increasing the number of successful collisions between reactant particles per unit time.

Question 22

Which reaction occurs fastest? 0, 1000 or 2000 degrees Celsius

Answer 22

The reaction at 2000oC.
Because the reaction at 2000oC has more kinetic energy than the reactions at 1000oC or 0oC ,at 2000oC there is a greater number of particles with energy greater than or equal to the activation energy (EA) compared to 1000oC or 0oC.
Therefore, there are more successful collisions between the reactant molecules per unit time.

Question 23

Explain how a catalyst increases the rate of reaction

Answer 23

Catalysts lower the activation energy of a reaction by providing an alternative pathway for the reaction to occur. This increases the proportion of particles with energy equal to or greater than the activation energy which results in a greater frequency of successful collisions per unit time