Electricity and Chemistry

6.1 - Define electrolysis

The breaking down of ionic compounds when molten or in aqueous solutions into simpler forms using electricity.

6.1 - TRUE OR FALSE
electricity moves from the negative side to positive side in the solution

FALSE
only ions move in an electrolyte, not electrons.

6.1 - Draw and label an electrolysis experiment.

Include:
- anode as the negative electrode
- cathode as the positive electrode
- the electrolyte as the molten/ aqueous substance that undergoes electrolysis

6.1 - Describe the transfer of charge during electrolysis.

Include:
a) the movement of electrons in the external circuit
b) the loss/ gain of electrons at the electrodes
c) the movement of ions in the electrolyte

6.1 - What materials can be used for inert electrodes?

carbon, graphite & platinum

6.1 - Identify the products formed at the electrodes and describe the observations made during the electrolysis of:
a) molten lead (II) bromide
b) concentrated aqueous sodium chloride
c) dilute sulfuric acid
using inert electrodes.

a) anode: Br
cathode: Pb
b) anode: Cl
cathode: H
c) anode: OH
cathode: H

6.2 - What is brine?

concentrated aqueous solution of sodium chloride.

6.2 - How is brine obtained?

seawater

6.2 - What machine is used to electrolyze brine? draw and label.

Diaphragm cell.

6.2 - What is produced during the electrolysis of brine?

chlorine, hydrogen & NaOH

6.4 - State the use of copper and why does it need to be purified.

- excellent conductor of electricity
- electrical wiring
- impurities reduce conductivity

6.4 - Draw and label the electrolysis of purifying copper (both with inert and metal electrodes)

6.4 - Describe the experiment of purifying copper using inert electrodes.

anode:
- X lose electrons
- oxygen gas bubbles off
cathode:
- copper is deposited
electrolyte:
- loses colour (copper ions in electrolyte turns into atoms at cathode)

6.5 - Why are metals electroplated? Give examples and explain.

i) protection of metals from corrosion
- hard, does not scratch easily
- tin cans, furniture, bicycle handes
ii) improving appearance
- shiny (gold and silver)
- for jewelry & cutlery

6.5 - Explain how metals are electroplated using copper.

cathode: object to be electroplated
anode: plating metal
electrolyte: plating metal
- copper is transferred from anode to cathode
- the colour of electrolyte X change
- copper ions removed from solution by cathode and is replaced by copper ions from anode