Chemicals from the Sea Flashcards
Where can sodium chloride (salt) be obtained?
From the sea or from salt deposits
Describe how salt can also be mined.
It is mined as rock salt and by solution mining in Cheshire.
Explain how mining for salt can lead to subsidence.
Solution mining leaves huge holes in the rock which can subside.
The electrolysis of concentrated sodium chloride or brine produces what gases?
It gives chlorine and hydrogen.
Recall that the chemical test for chlorine
It bleaches moist litmus paper.
Recall the products of the electrolysis of concentrated sodium chloride solution (brine)
- hydrogen made at the cathode
- chlorine made at the anode
- sodium hydroxide is also made.
Explain why it is important to use inert electrodes in the electrolysis of sodium chloride solution.
The chlorine would react with the electrodes and destroy them.
What ions are there in the electrolysis of sodium chloride solution (brine)
NaCl(aq) contains Na+, OH-, Cl-, H+
What happens at the cathode
Cathode 2H+ + 2e- –> H2
What happens at the anode
Anode 2Cl- —> Cl2 + 2e-
What is left in solution
Ions not discharged make Sodium Oxide.
Why does the electrolysis of sodium chloride involve both reduction and oxidation?
Oxidation is loss of electrons, reduction is gain of electrons. (OIL RIG)
Recall the uses of sodium chloride
As a preservative and as a flavouring
Why is sodium chloride is an important raw material
It is used a lot in the chemical industry, including use as a source of chlorine and sodium hydroxide.
Name some household substances made from substances made from salt.
Household bleach, pvc(plastics) and solvents
