Topic 5 - Chemical Reactions

Question 0

Is bond breaking an endothermic or exothermic process?

Answer 0

Endothermic

Question 1

What is needed to break bonds?

Answer 1

Energy

Question 2

Is bond formation an endothermic or exothermic process?

Answer 2

Exothermic process

Question 3

What is an endothermic reaction?

Answer 3

Where there is a decrease in temperature in the surroundings and heat energy is taken in. Ie photosynthesis

Question 4

What is an exothermic reaction?

Answer 4

When there is an increase in temperature in surroundings and heat energy is given out. Ie respiration

Question 5

Are physical reactions reversible or irreversible?

Answer 5

Reversable

Question 6

Are chemical reactions reversible or irreversible?

Answer 6

Irreversable

Question 7

In chemical reactions, do the reactants turn to products, or the products turned to reactants?

Answer 7

reactants turn to products

Question 8

How to calculate the rate of a reaction?

Answer 8

Rate = amount of reactant used or product formed / time taken

Question 9

What does BENDOMEX stand for?

Answer 9

B reaking bonds is ENDO thermic

M aking bonds is EX othermic

Question 10

What are catalysts?

Answer 10

Substances that speed up chemical reactions without being used up in the reaction

Question 11

Why do people want to speed up a reaction?

Answer 11

To save time / reduce production time

Gain money

Question 12

What is activation energy

Answer 12

The minimum energy needed to start a reaction.

Question 13

What is a catalytic converter made out of?

Answer 13

Platinum or another similar metal

Question 14

What does a catalytic converter do

Answer 14

Converts gases into water vapour and less harmful gases to reduce harmful emissions

Question 15

What does a catalytic converter have a honeycomb structure

Answer 15

To give the catalyst a larger surface area

Question 16

What temperature for catalytic converters work best at?

Answer 16

430’C

Question 17

Is burning fossil fuels exothermic or endothermic?

Answer 17

Exothermic - heat is given out to surroundings

Question 18

Is photosynthesis exothermic or endothermic?

Answer 18

Endothermic - uses energy from sun to convert water and CO2 into O2 and glucose

Question 19

How would you measure the temperature during any of these reactions:

Dissolving salts in water
Neutralisation reactions
Displacement reactions
Precipitation reactions

Answer 19

• Take the temperature of the reactants (making sure they’re the same) - Mix them in a polystyrene cup and measure the temperature of the solution at the end of the reaction
• Put cup into beaker of cotton wool to give more insulation and putting a lid on top to stop energy lost by evaporation

Question 20

What does the rate of a reaction depend on?

Answer 20

Temperature
Surface area of a solid (or size of particles)
Concentration (or pressure for gases)
Catalyst

Question 21

What is the result of a larger surface area in hydrochloric acid and marble chip reaction?

Answer 21

Larger surface area = more collisions = greater chance of successful collisions = rate of reaction is faster

Question 22

How does a more concentrated acid affect a hydrochloric acid and marble chip reaction?

Answer 22

There are more reactant particles in the same volume
There is a greater chance of the particles colliding
The rate of reaction increases

Question 23

If a solid reactant is broken into small pieces or ground into a powder:

Answer 23

Its surface area is increased
More particles are exposed to the other reactants
There is a greater chance of the particles colliding
The rate of reaction increases

Question 24

If the temperature is increased in hydrochloric and marble chip reactiom

Answer 24

The reactant particles move more quickly
More particles have the activation energy or greater
The particles collide more often, and more of the collisions result in a reaction
The rate of reaction increases

Question 25

Using a catalyst

Answer 25

Catalysts increase the rate of reaction without being used up.
They do this by lowering the activation energy needed for the particles to start reacting with each other.

Catalysts are important in industry because they reduce costs.

Question 26

What does a catalytic converters converter do?

Answer 26

Converts harmful gases into water vapour and other less harmful gases to reduce harmful emissions

Question 27

Why is it important in industry to keep waste products to a minimum

Answer 27

• it costs money to dispose of them properly
• they don’t make any profit / no commercial benefits
• bad for environment

Question 28

What is the melting point of potassium chloride

Answer 28

800’C