Electrochemical cells - Background

Question 1

What does this topic set about?

Answer 1

comparing the ease with which a metal gives away electrons and form positive ions

Question 2

What happens if a metal strip is placed in water?

Answer 2

• there will be a tendancy for the magnesium atoms to shed electrons and go into solution as magnesium ions
• these electrons will be left behind on the magnesium

Question 3

What happens as the electrons build up in the magnesium?

Answer 3

• positive ions attracted to the negative charge on the piece of metal
• some of them will be attracted enough that they will reclaim their electrons and stick back on to the piece of metal

Question 4

What would the difference between copper and magnesium in water?

Answer 4

• copper less reactive than magnesium
• forms ions less readily
• ions that form more likely to reclaium there electrons
• less charge on metal, fewer ions in solution
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Question 5

What is the half equation for magnesium?

Answer 5

• Mg²⁺(aq) + 2e^- ⇌ Mg(s)
• by convention , electrons on left

Question 6

What is the potential differnece of the metal in water?

Answer 6

• differnece between the positiveness and the negativeness
  
  • bigger the difference bigger the PD
• could be written as a voltage
  
  • although its impossible to measure

Question 7

Why is the voltage impossible to measure

Answer 7

• voltmeter could be connected to metal
• any probe in solution would have a similar equilibrium acting around it.