Chemistry- Halogens Flashcards
Reaction of chlorine with water (equation)
Cl2(aq) + H2O(l) –> HClO(aq) +HCl (aq)
DISPOPORTIONATION
What is the reaction of chlorine with water used for?
Used in the production of drinking water, as it kills harmful bacteria.
How does it kill harmful bacteria
Both products are acids, chloric acid and hydrochloric acid. Bacteria killed by chloric (I) acid and chlorate (I), ClO- ions.
Production of bleach equation
Cl2(aq) + 2NaOH(aq) —> NaClO(aq) + NaCl(aq) + H2O(l)
DISPROPORTIONATION
What are the conditions required for this reaction?
NaOH must be cold, dilute and aqueous.
Advantages of Chlorinating drinking water
-Destroys microorganisms that cause disease.
-Long lasting
-Reduces growth of algae.
Disadvantages of chlorinating drinking water
-Chlorine gas is toxic
-Liquid chlorine causes severe chemical burns to skin.
-Chlorine can react with organic compounds to form chloroalkanes which have been linked with causing cancer.
In Halogen Displacement reactions- what does the colour of the solution in the test tube show?
Which free halogen is present in solution.
What does the colour of the organic solvent show?
Which free halogen is present in solution.
What colour is Cl2 when in aqueous solution?
Very pale green/ Colourless
solution.
What colour is Br2 when in aqueous solution?
Yellow Solution
What colour is I2 when in aqueous solution?
Brown solution (sometimes black solid present).
Why is organic solvent added?
To make the colour change more obvious.
What colour is Cl2 in the organic layer?
Colourless
What colour is Br2 in the organic layer?
Yellow
