C2h-chemicals From The Sea:sodium Chloride Flashcards
(19 cards)
What is solution mining?
Pumping hoy water underground
Salt dissolves
Salt solution forced to surface by pressure of water
How can mining for salt lead to subsidence?
If holes dug out after mining are not filled
Leads to land collapsing and sliding into hole
What are the 2 methods of extracting salt?
Mined as rock salt
Solution mining
What is the test for chlorine?
It bleaches damp litmus paper
What are the products of the electrolysis of concentrated sodium chloride solution (brine)?
Hydrogen
Chlorine
Sodium hydroxide
Why are inert electrodes used in the electrolysis of sodium chloride solution?
So they won’t react with the electrolyte or the products of electrolysis
What ions does sodium chloride solution contain?
Na+
OH-
Cl-
H+
What happens at the cathode?
Two hydrogen ions accept one electron each to become one hydrogen molecule
Hydrogen is made
Reduction
What happens at the anode?
Two chloride ions lose one electron each to become one chlorine molecule
Chlorine is made
Oxidation
What is the half equation for the reaction at the cathode?
2H+ + 2e –> H2
What is the half equation for the reaction at the anode?
2Cl- - 2e –> Cl2
How is sodium hydroxide formed?
Ions left in solution form sodium hydroxide
What is sodium chloride used as?
Preservatives
Flavourings
What is sodium chloride a source of?
Chlorine
Sodium hydroxide
What is chlorine used for?
Sterilise water
Make solvents
Household bleach
Plastics
What is hydrogen used for?
Ammonia
Margarine
What is sodium hydroxide used for?
Soap
Household bleach
How is household bleach made?
Sodium hydroxide reacted with chlorine
Sodium hydroxide + chlorine–> sodium chloride + water+ sodium chlorate
Why is the chlor-alkali industry important for the economy?
Lots of new products made
Lots of jobs created
Eg
Ammonia, plastics, bleach, soap
