Batteries, Fuel Cells and Corrosion: Quiz
Seven questions on batteries, fuel cells, rusting and corrosion protection, with explanations.
Batteries, Fuel Cells and Corrosion: Quiz
7 questions
Charging is electrolysis: electrical energy forces the non-spontaneous reverse reaction, restoring the reactants.
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Answer: An external current drives the cell reaction in reverse
Charging is electrolysis: electrical energy forces the non-spontaneous reverse reaction, restoring the reactants.
Overall reaction: 2H₂ + O₂ → 2H₂O.
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Answer: Water
Overall reaction: 2H₂ + O₂ → 2H₂O.
Rusting needs oxygen and water; dissolved salt makes the water a better electrolyte and speeds the reaction.
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Answer: Salt water open to air
Rusting needs oxygen and water; dissolved salt makes the water a better electrolyte and speeds the reaction.
Magnesium (E° −2.37 V) is oxidized more easily than iron (−0.44 V), so it corrodes instead. Copper, silver and tin are less reactive than iron.
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Answer: Magnesium
Magnesium (E° −2.37 V) is oxidized more easily than iron (−0.44 V), so it corrodes instead. Copper, silver and tin are less reactive than iron.
E°cell = E°cathode − E°anode = 1.23 V − (−0.44 V) = 1.67 V. 0.79 V comes from adding the values.
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Answer: 1.67 V
E°cell = E°cathode − E°anode = 1.23 V − (−0.44 V) = 1.67 V. 0.79 V comes from adding the values.
ΔG° = −4 × 96 485 C/mol × 1.23 V = −475 kJ for 2 mol H₂, which is −237 kJ per mole of H₂.
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Answer: −237 kJ
ΔG° = −4 × 96 485 C/mol × 1.23 V = −475 kJ for 2 mol H₂, which is −237 kJ per mole of H₂.
Where both metals touch the electrolyte, the more reactive iron is oxidized and the tin acts as the cathode, speeding corrosion of the iron.
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Answer: Iron becomes the anode, because iron is more reactive than tin
Where both metals touch the electrolyte, the more reactive iron is oxidized and the tin acts as the cathode, speeding corrosion of the iron.