Rates and Equilibrium

Question 1

What are the two ways that the rate of reaction can be measured

Answer 1

Amount of product used up over time
Amount of reactant used up over time

Question 2

If we have a graph with amount of product or reactant used up over time, with a curve of best fit, how can we measure the rate of reaction at a given time

Answer 2

Measure the gradient by drawing a tangent to the curve at that point

Question 3

What does the collision theory state

Answer 3

Particles must collide with a minimum amount of energy before they can react with each other

Question 4

What is the minimum amount of energy that particles must react with called

Answer 4

Activation energy

Question 5

What happens to the rate of reaction if the surface area to volume ratio of any solid reactants increases

Answer 5

The rate of reaction increases

Question 6

What is the effect on the rate of reaction if the temperature is increased, and why

Answer 6

The rate of reaction increases because:
the particles collide more frequently, due to the added kinetic energy
the particles collide with more energy

Question 7

What is the effect of increasing the concentration of reactants in a solution

Answer 7

Rate of reaction increases because the particles will collide more frequently

Question 8

What is the effect of decreasing the pressure in a gas

Answer 8

The rate of reaction decreases as the gas particles react less frequently

Question 9

What is a catalyst

Answer 9

A substance which speeds up the rate of reaction, without being used up, by providing an alternate reaction pathway

Question 10

What happens to the activation energy of a reaction when a catalyst is used

Answer 10

The activation energy is lowered

Question 11

What are some advantages of catalysts in industry

Answer 11

• cheaper to use a catalyst than pay for the extra energy needed without one, helping the environment

Question 12

What is a reversible reaction

Answer 12

A reaction where the products formed can react to make the original reactants

Question 13

What symbol is used in a reversible reaction

Answer 13

⇌

Question 14

True or False: both reactions in a reversible reaction are exothermic

Answer 14

False - One reaction is endothermic and one is exothermic

Question 15

Define equilibrium

Answer 15

Thee state of a reaction where the rate of the forward reaction equals the rate of the reverse reaction, in a closed system

Question 16

Explain how a reversible reaction reaches equilibrium

Answer 16

Initially, only the forward reaction occurs because there are no products formed yet

The rate of the backwards reaction increases, but is still lower than the rate of the forward reaction because there are less products

The rate of the backwards reaction gradually becomes higher than the rate of the forward reaction as there are fewer reactions now

This process continues until the rate of the forwards and backwards reactions are equal

Question 17

What does Le Chatelier’s principle state

Answer 17

If an external condition is introduced to a reversible reaction at equilibrium, the equilibrium will shift to cancel out that change

Question 18

What is the structure used to answer a rate of reactions question

Answer 18

Shift Favour Why

Question 19

What reaction in a reversible reaction does equilibrium favour if the temperature increases

Answer 19

The endothermic direction is favoured

Question 20

What reaction in a reversible reaction does equilibrium favour if the pressure increases

Answer 20

The reaction which produces the least amount of products