6.3 Electrolysing brine
Brine is salty water. It’s
chemical name is sodium
chloride, NaClaq. Both
elements are useful in
thousands of products.
13 April 2015
6.3 Electrolysing brine
13 April 2015
• Brine can be electrolysed into
– Sodium Hydroxide (NaOH)
– Chlorine (Cl)
– Hydrogen (H2).
• Some of the uses of the products of
the electrolysis of brine are;
–
–
–
–
Soap (NaOH)
PVC (Cl)
Bleach (NaOH + Cl)
Margerine (H2)
Diaphragm cell
What type of ion does chlorine
form? What type of ion for
hydrogen?
Sodium is more reactive than Hydrogen so does not
gather at the cathode.
Wear Eye Protection.
Practical
Caution: Sodium Hydroxide
Chlorine
Method
1. Set up the apparatus
as shown.
2. Write down your
observations as shown
below.
Diagram
6V
Results
Electrode
Anode
(+)
Cathode
(-)
Observations
Beaker with
saturated brine
and Universal
Indicator
Questions
1. Name the gas given off at each electrode.
2. What are the four ions present in the
brine?
3. Which ions remain in the solution?
4. What compound would they form?
Answers
1.
Name the gas given off at each electrode.
•
Anode = Chlorine, Cathode = Hydrogen
2. What are the four ions present in the brine?
•
Sodium+, Chloride-, Oxide2-, Hydrogen+
3. Which ions remain in the solution?
•
Sodium+, Oxide2-, Hydrogen+
4. What compound would they form?
•
Sodium Hydroxide (NaOH)
Uses of electrolysed brine
Brine produces 3 main products. Which products are
used for;
NaOH
H
Cl
1.
2.
3.
4.
5.
6.
7.
8.
9.
Margarine
PVC
Bleach
Soap
Paper
Rayon fibres
Detergents
Purification of aluminium ore
Hydrochloric acid manufacture
2
Uses of electrolysed brine
1.
2.
3.
4.
5.
6.
7.
8.
9.
Margarine [hydrogen]
PVC [chlorine]
Bleach [sodium hydroxide, chlorine]
Soap [sodium hydroxide]
Paper [chlorine]
Rayon fibres [sodium hydroxide]
Detergents [sodium hydroxide, chlorine]
Purification of aluminium ore [sodium hydroxide]
Hydrochloric acid manufacture [chlorine, hydrogen]
6.3 Electrolysing brine
13 April 2015
• Brine can be electrolysed into
– Sodium Hydroxide (NaOH)
– Chlorine (Cl)
– Hydrogen (H2).
• Some of the uses of the products of
the electrolysis of brine are;
–
–
–
–
Soap (NaOH)
PVC (Cl)
Bleach (NaOH + Cl)
Margerine (H2)