chemical cells

• What do chemical cells use to transfer energy?

  Chemical reactions
• What does the voltage of a cell depend on?

  It depends on the electrodes and the electrolyte used
• What is a simple cell made from?

  Two different metals in contact with an electrolyte
• How is a battery formed from cells?

  A battery is formed by connecting multiple cells in series
• What happens to non-rechargeable cells when one of the reactants is used up?

  The battery 'goes flat'
• How can the chemical reactions in rechargeable cells be reversed?

  By supplying an external circuit
• What is the most reactive metal in the simple reactivity series provided?

  Magnesium
• What is the relationship between the reactivity of metals and the voltage produced in a cell?

  The biggest voltage occurs when the difference in reactivity is the largest
• What happens to the voltage when different combinations of metals are connected in a cell?

  The voltage changes based on the reactivity of the metals
• What do fuel cells require to produce voltage continuously?

  A constant supply of fuel and oxygen
• How is the fuel oxidized in fuel cells?

  Electrochemically, rather than being burned
• What is the only product of a hydrogen-oxygen fuel cell?

  Water
• What is the overall reaction in a hydrogen-oxygen fuel cell?

  Hydrogen + Oxygen → Water
• What are the half equations at the negative and positive electrodes in a hydrogen-oxygen fuel cell?

  Negative: $2H_2 +$$4OH^- → 4H_2O +$$4e^-$; Positive: $O_2 +$$2H_2O +$$4e^- → 4OH^-$
• What happens when the two half equations in a hydrogen-oxygen fuel cell are added together?

  The hydroxide ions, electrons, and two H2O molecules cancel out
• What are the pros of alkaline cells?

  They are cheaper to manufacture
• What is a con of rechargeable cells?

  They cost more to manufacture
• What is a strength of hydrogen fuel cells?

  They are easy to maintain with no moving parts
• Why are hydrogen-oxygen fuel cells used in spacecraft?

  They provide drinking water for astronauts
• What is a con of hydrogen fuel cells?

  They are very expensive to manufacture
• What is a potential problem for hydrogen-oxygen fuel cells in spacecraft?

  They need a constant supply of hydrogen fuel
• How can hydrogen and oxygen be replaced in spacecraft in orbit?

  Through the electrolysis of water
• When do solar cells work effectively?

  When they are in the light
• What advantage do fuel cells provide for spacecraft in the dark?

  They allow electricity to be produced