Alkalis, chlorine, etc. Why & How Flashcards
What uses did alkalis have even before industrialisation?
neutralise acid soils, make chemicals that bind natural dyes to cloth, convert fats and oils into soap and to manufacture
glass
How did we previously get alkalis?
From burnt wood and stale urine
What are examples of soluble alkalis and how do they react with acids?
Soluble hydroxides and carbonates are alkalis that neutralise acids forming salts
What was the first process for manufacturing an alkali and what were the issues with it?
The Leblanc process made sodium carbonate by reacting salt and limestone, heating them with coal, it produced large amounts of pollution: acid gas (hydrogen chloride) and galligu which produces hydrogen sulfide.
How were the products of the Leblanc process later used?
Hydrogen chloride was turned into chlorine used to bleach textiles prior to dying and hydrochloric acid was used to make other chemicals
What were the effects and benefits of adding chlorine to water?
Chlorination of water kills the bacteria in water and made Britain much healthier, it rid water supplies of typhoid and cholera.
What are the potential risks of the chlorination of water?
Chlorine can react with organic materials in water supplies and can cause toxic or carcinogenic compounds to be formed, these are called disinfectant by products (DBPs)
What does electrolysis do?
Runs a current through a chemical solution and can bring about a chemical change and make new chemical products
What is electrolysis mainly used for?
It is used to obtain chlorine by the electrolysis of brine (a salt solution)
How does the electrolysis of brine work?
Brine is put into a compartment with an anode (positive electrode) and water into another compartment connected by a membrane, containing a negative cathode.
What is produced by electrolysis and how?
Chlorine gas is produced in the side of the anode, hydrogen gas is produced on the side of the cathode and so is the sodium hydroxide solution
What are the uses of the products of the electrolysis of brine?
Chlorine is used in making plastics like PVC, in medicines and crop protection,
Hydrogen for making margarine, rocket fuel and fuel in vehicles,
Sodium hydroxide for paper recycling, industrial cleaners and refining aluminium
What are the environmental impacts of the products of the electrolysis of brine?
Chlorine products have been linked to the depletion of the ozone layer, chlorine used in paper bleaching can cause cancer
