chemistry - electrolysis

Question 1

how do you set up a general electrolysis experiment?

Answer 1

• place the positive and negative electrodes in a beaker containing a molten or dissolved ionic compound
• connect both electrodes to a power supply with wires

Question 2

how can you investigate what happens when an aqueous solution of CuCl2 is electrolysed?

Answer 2

• half fill a beaker with aqueous CuCl2
• place a lid on the beaker and insert the electrodes into the solution through holes in the lid (electrodes must not touch)
• connect the electrodes to a low voltage power supply
• switch the power supply on to 4V
• turn off the power after a few minutes and record any observations made

Question 3

what forms at each electrode (include the name of each electrode)?

Answer 3

Cathode - metals or hydrogen
Anode - non metals

Question 4

what would you observe at each electrode when copper chloride solution is electrolysed?

Answer 4

positive electrode: bubbles of gas (chlorine)
negative electrode: electrode coated with a brown solid (copper)

Question 5

why must the anode (positive electrode) be regularly replaced?

Answer 5

the positive electrode is made of carbon and will react with oxygen to produce carbon dioxide

Question 6

in the electrolysis of NaCl, hydrogen is produced at the cathode. Why is sodium not produced?

Answer 6

• hydrogen is produced because sodium is more reactive is more reactive than hydrogen.
• sodium remains in the solution