1.5 Kinetics

Question 1

How do you work out rate of reaction?

Answer 1

Rate of reaction=amount of product formed(or amount of reactant used)/time

Question 2

According to collision theory what 2 things need to happen for a reaction to take place?

Answer 2

1. The reactants need to collide in the correct orientation 2. The reactants must have enough energy to overcome the bonding and repulsive forces which is known as the activation energy

Question 3

What 5 factors affect rates of reaction?

Answer 3

1. Temperature 2. Concentration 3. Pressure 4. Surface area 5. Catslyst

Question 4

Why does the Maxwell-Botzmam distribution graph start at 0,0?

Answer 4

Because no particles have no energy

Question 5

What does the area under the curve represent?

Answer 5

The total number of particles

Question 6

What is the effect of concentration on a reaction?

Answer 6

If there is a higher concentration there will be more of the reactant in the same volume solution which means that there will be more particles with the chance of colliding with enough energy to begin reacting. This increases the rate of reaction.

Question 7

What effect does temperature have on rate of reaction?

Answer 7

A higher temperature means that particles will move faster and will on average have more kinetic energy. This means they will collide more often and they have a greater chance of having enough energy to begin reacting. This speeds up the rate of reaction.

Question 8

What effect does increasing the pressure of a gas in a reaction do?

Answer 8

Raising the pressure pushes the particles closer together making them more likely to collide. This increases the rate of reaction.

Question 9

Define a catalyst

Answer 9

A catalyst is a substance that increases the rate of reaction by providing an alternative reaction pathway with a lower activation energy. The catalyst is chemically unchanged at the end of the reaction.

Question 10

What is Le Chatelier’s principle of the position of equilibrium in a reversible reaction?

Answer 10

If a reaction at equilibrium is subjected to a change in concentration, pressure or temperature, the position of equilibrium will move to counteract the change.

Question 11

When is a dynamic equilbrium achieved by a reversable reaction?

Answer 11

When the concentrations of the reactants and products stay constant. This is only possible in a closed system.

Question 12

What effect does increasing the concentration of a reactant have?

Answer 12

The position of equilibrium will shift to the right as the reaction creates more product to use up the excess reactant

Question 13

What effect does increasing the pressure of a reaction with gases have on the position of equilibrium?

Answer 13

The position of equilibrium will shift to the side with fewer gas molecules (fewer moles in the equation) to reduce the pressure

Question 14

What effect does increasing the temperature have on the position of equilibrium?

Answer 14

When you add the position of equilibrium shifts towards the endothermic reation to try and reduce the heat of the reaction

Question 15

What effect does adding a catalyst have on the position of equilibrium?

Answer 15

It has no effect as the catalyst speeds up both reactions

Question 16

What other effect does reducing the temperature have apart from favouring the exothermic reaction?

Answer 16

It slows down the rate of reaction

Question 17

Why in industry may companies choose to go for a lower pressure even when a higher pressure produces a higher yield?

Answer 17

Because the pipes and containers for high pressures are extremely expensive. It also has a higher chance of dangerous accidents occuring so more expensive safety measures have to be taken.

Question 18

What goes on the X and Y axis of the Maxwell-Boltzman distibution curve?

Answer 18

X is energy, Y is fraction of particles with energy, E