Cells

Question 1

How to produce electricity

Answer 1

Take two different metals and place them into an electrolyte

Question 2

Describe an electrolyte

Answer 2

A solution that can conduct electricity

Question 3

Disadvantage of a cell

Answer 3

• Can only produce electricity for a certain period of time
  = eventually chemicals in cell run out and reaction stops
• Cells only produce electricity if we use metals with different reactivities

Question 4

Describe potential difference of a cell

Answer 4

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

Question 5

Describe a battery

Answer 5

Contains two or more cells connected in a series to produce a greater voltage

Question 6

How do we recharge batteries

Answer 6

Reverse chemical reactions when we apply electrical current

Question 7

What happens in a fuel cell

Answer 7

React hydrogen with oxygen

Question 8

Negative electrode half equation of a fuel cell

Answer 8

2H2 = 4H + 4e-

Question 9

Positive electrode half equation of a fuel cell

Answer 9

O2 + 4H + 4e- = 2H2O

Question 10

Overall equation of a fuel cell

Answer 10

2H2 + O2 = 2H2O

Hydrogen is being oxidised

Question 11

Adv of hydrogen fuel cells

Answer 11

• take less time to refuel
• travel further without refuelling
• don’t get less efficient the longer get they run
• can be a source of drinking water
• water is only product no carbon emissions

Question 12

Disadvantages of rechargeable batteries

Answer 12

• they run out and must be recharged
• can store less electricity the more charging cycles they go through

Question 13

Disadvantages of hydrogen fuel cells

Answer 13

• run on hydrogen which is an explosive gas and difficult to store safely
• produce a low potential difference
• production of hydrogen uses fossil fuels
• not sold everywhere

Question 14

Advantages of rechargeable batteries

Answer 14

• no dangerous fuels are required
• can produce a greater potential difference than a hydrogen fuel cell
• reversible reaction
  = pass electricity through battery causing reaction to go in reverse direction
  = recharging the reactants