C5: CHEMICAL CELLS AND FUEL CELLS

Question 1

What is a chemical cell?

Answer 1

a simple chemical cell can be made by connecting 2 different metals in contact with an electrolyte

Question 2

Factors affecting voltage produced by a chemical cell

Answer 2

-type of electrode
-type of electrolyte
-conc of electrolyte
-temp

Question 3

What is a fuel cell?

Answer 3

an electrical cell that produces a voltage continuously as long as it is supplied with:
-a fuel
-O2

Question 4

How do hydrogen-oxygen fuel cells work?

Answer 4

-the electrolyte is often an acid (eg: phosphoric acid) the electrodes are often porous carbon with a catalyst
-hydrogen goes into the anode (-ve) compartment and oxygen goes into the cathode (+ve) (in fuel cells the anode is -ve and the cathode is +ve)
-at the anode hydrogen loses electrons to produce H^+ ions (oxidation)
-H^+ ions move to the cathode
-at the cathode oxygen gains electrons from the cathode and reacts with H^+ ions to make water (reduction)
-electrons flow through an external circuit from the anode to the cathode (this is the electric current)
-the overall reaction is:
2H2 + O2 –> 2H2O

Question 5

Advs of fuel cells

Answer 5

-only produce water
-saves fossil fuel resources
-don’t need to be recharged
-cheaper than batteries
-store more energy than batteries

Question 6

Disadvs of fuel cells

Answer 6

-difficult to safely store hydrogen as it is explosive when mixed with air
-takes up more space than a battery as it is a gas
-hydrogen fuel is produced from non-renewable sources