ES 5- Risks And Benefits Of Chlorine Flashcards
What is chlorine used for?
- water treatment (kills bacteria/pathogens)
- bleach ( kills bacteria and removes stains by breaking bones in coloured compounds)
Why would chlorine be used as a weapon?
- is a toxic gas
- causes irritation to eyes, skin and respiratory system at low doses (1ppm)
- above 40ppm, reacts with water in lungs forming HCl, and destroying tissue
Why is chlorine transported in pressurised tanks?
- pressure turns gas into liquid form so more can be transported
Why do the pressurised tanks used for transporting chlorine have valves?
- if pressure gets too high, small amount can be released
- better to release small amount than risk large explosion
Why must the pressurised tanks used for transporting chlorine be completely dry?
- would react with water to form corrosive acids and cause leakages
Describe how chlorine is unloaded from rail tanker
- Chlorine is transferred to bulk tanker using protected transfer pipes
- The air that is displaced in bulk tanker contains chlorine so cannot be released, is put into scrubber
- Scrubber contains NaOH, whihc reacts with Cl to form sodium chlorate(I), household bleach
What are leaks of chlorine detected by, and what is the result?
- detected by conc ammonia
- white precipitate is formed, looks like cloud
Iodine-thiosulfate titration is what type of titration?
Redox
What is iodine-thiosulfate titration used for?
To determine concentration of chemical that is strong enough to oxidise iodide ions
What is the first step of iodine-thiosulfate titration?
Excess iodide ions are added to bleach, iodine produced is reacted with thiosulphate ion
What is the end of iodine-thiosulfate titration identified by?
Starch- when blue/black colour has turned colourless, iodine is no longer present
