C2 - Chemicals from the sea Flashcards
What is the chemical name for salt?
Sodium chloride.
State three ways in which salt is used.
- as a preservative and to give flavor
- scattered on roads as grit
- in the chemical industry
What are the two ways in which salt is extracted?
1) water is pumped into the rock where salt dissolves. The solution is pumped back up where the water is evaporated
2) underground cutting machines extracts salt but it is impure
What is subsidence?
When the ground begins to sink because salt has been extracted.
What is hydrogen used for?
Making margarine.
What is sodium hydroxide used for?
To make soap.
What is chlorine gas used for?
Sterilizing drinking water.
What is the chemical test for chlorine?
Hold litmus paper in a test tube of gas. It will turn white if chlorine is present.
During electrolysis of sodium chloride, what is formed at the anode?
Chlorine.
Why must electrodes be inert?
Because hydrogen and chlorine are reactive.
What two chemicals can be reacted together to make domestic bleach?
Chlorine and sodium hydroxide.
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
