Halogens

Question 1

State of bromine

Answer 1

Red/ brown liquid

Question 2

State of iodine

Answer 2

Black solid

Question 3

Cl2 when in
water
cyclohexane

Answer 3

Pale green

Question 4

Br2 when in
Water
Cyclohexane

Answer 4

Orange

Question 5

I2 when in
Water
Cyclohexane

Answer 5

Brown

Purple

Question 6

Purpose of chlorine in water purification

Answer 6

Kills pathogen to avoid disease

Chlorine reacts with water to form acidic solution that kills pathogens

Question 7

Chlorine and water reaction

Answer 7

Forms

hydrochloric acid

Chloric acid (HOCl)

Question 8

Why is Cl2 reaction with H2O disproportionation reaction

Answer 8

Chlorine is both oxidised and reduced

Oxidised on HOCl
Reduced in HCl

Question 9

Risks of using chlorine to purify water

Answer 9

Gas is toxic

Chlorinated hydrocarbon may form which are carcinogenic

Question 10

Benefits of Chlorine purifying water

Answer 10

Kills many harmful microorganisms

Reduces rates of waterborne disease; cholera and typhoid

Question 11

How is bleach created

Answer 11

Cl2 and cold dilute NaOH

Forms NaOCl and NaCl

NaOCl is the bleach

Question 12

State and colour of chlorine

Answer 12

Yellow/ green gas

Question 13

Describe trend in boiling point down the group.

Answer 13

• Increases
• Greater amount of electrons down the group means that there are stronger London forces between the molecules
• Thus requiring greater energy to break the attraction

Question 14

Describe the test for halide ions.

Including ionic equation.

Answer 14

• Add AgNO3 to unknown solution
• Precipitation reaction will form a Silver halide
• X- + Ag+ = AgX
• Colour of the ppt indicates the type of halide ion;
  White- Chloride
  Cream- Bromide
  Yellow- Iodide

The further distinguish, NH3 is added;
Dilute NH3 dissolves Cl- but not Br-
Concentrated NH3 dissolves Br-