C7

Question 1

Draw an exothermic reaction profile?

Answer 1

draw

Question 2

Draw an endothermic reaction profile?

Answer 2

draw

Question 3

draw an electrolysis cell?

Answer 3

draw

Question 4

Advantages of hydrogen fuel cells

Answer 4

• They will produce electricity for as long as you provide hydrogen
• Hydrogen fuel cells do not get less efficient the longer they run

Question 5

Bond Energy Formula?

Answer 5

energy change = sum of the energy needed to break bonds (reactants) - energy released when new bonds are formed (products)

Question 6

Characteristics of fuel cells?

Answer 6

• reliable
• efficient
• compact and lightweight
• not very polluting

Question 7

Disadvantages of hydrogen fuel cells

Answer 7

• Highly Explosive
• They produce a relatively low potential difference or voltage so several are needed together

Question 8

Electrolysis and photosynthesis is an example of a _____.

Answer 8

endothermic reaction

Question 9

Example of a endothermic reaction

Answer 9

citric acid + sodium hydrogencarbonate

Question 10

Example of reactive profile diagram with catalyst

Answer 10

draw

Question 11

How can rechargeable batteries be recharged?

Answer 11

The chemical reactions can be reversed when an electrical current is applied.

Question 12

How does the reactivity of the metals link to the potential difference of the metals?

Answer 12

The greater the difference between the reactivity of the metals, the greater the potential difference produced by the cell.

Question 13

How is a electrochemical cell set up?

Answer 13

1) 2 electrodes which are metals as they must conduct electricity
2) The electrolyte is a liquid that contains ions
3) Wire connecting the 2 electrodes

Question 14

If the energy change on an energy level diagram is negative, is this an endothermic or exothermic reaction?

Answer 14

Exothermic reactions have a negative energy change because they release/lose energy.

Question 15

In an ____ reaction, the energy of the reactants is higher than the energy of the products.

Answer 15

exothermic

Question 16

In exothermic reactions the energy released by forming bonds is ____ than the energy used to break them.

Answer 16

greater

Question 17

Is bond breaking endothermic or exothermic?

Answer 17

endothermic

Question 18

Melting is an example of an _____.

Answer 18

Endothermic reaction. Energy is taken in from the surroundings.

Question 19

Name 2 different types of reactions which are exothermic

Answer 19

• Neutralisation
• Combustion

Question 20

Types of batteries

Answer 20

• rechargeable
  = non-rechargeable

Question 21

What can we do to change the voltage output of a cell?

Answer 21

• change the electrodes
• change the electrolyte

Question 22

What do catalysts do to the activation energy?

Answer 22

Catalysts increase reaction rates by lowering the activation energy

Question 23

What is a battery?

Answer 23

A battery contains 2 or more cells connected in series, to produce a greater voltage.

Question 24

What is a chemical cell?

Answer 24

A chemical cell is a source of electrical energy.

Question 25

What is a fuel cell?

Answer 25

A fuel cell is an electrical cell that's supplied with a fuel and oxygen which uses energy from the reaction between them to provide electrical energy efficiently.

Question 26

What is a reaction profile diagram?

Answer 26

Reaction profiles are diagrams that show the energies of the reactants and products in a reaction and how they change over the course of the reaction.

Question 27

What is activation energy?

Answer 27

Activation energy is the amount of energy required to start a chemical reaction

Question 28

What is an electrolyte?

Answer 28

A solution that can conduct electricity, usually an ionic compound

Question 29

What is an endothermic reaction?

Answer 29

An endothermic reaction is a reaction where energy is drawn in from the surroundings, causing the surroundings and object to cool down.

Question 30

What is an exothermic reaction?

Answer 30

An exothermic reaction is a reaction which cools itself down, giving heat to the surroundings.

Question 31

What is an instant cold ice pack an example of?

Answer 31

An endothermic process

Question 32

What is the only waste product in a hydrogen fuel cell?

Answer 32

water

Question 33

What type of process is the breaking of existing bonds?

Answer 33

endothermic

Question 34

What type of process is the forming of new bonds?

Answer 34

exothermic

Question 35

Which energy resource uses falling water to generate electricity?

Answer 35

Hydroelectricity

Question 36

Why are fuel cells reliable?

Answer 36

They have no moving parts

Question 37

Why can alkaline batteries not be recharged?

Answer 37

The reaction isnt reversible

Question 38

Why do alkaline batteries eventually stop working?

Answer 38

A reactant is used up