Practical activity

Determining a reactivity series

There are a number of ways that you could determine a reactivity series in Chemistry. This is an outline of the steps needed for one of these methods.

Aim

To determine the reactivity series of the halogens.

Method

  1. in three separate test tubes add some potassium chloride, potassium bromide, and potassium iodide
  2. using a pipette, add some chlorine water to the potassium bromide solution, and potassium iodide solution
  3. observe and record what happens to the potassium bromide solution, and potassium iodide solution
  4. repeat step 1
  5. using a pipette, add some bromine water to the potassium chloride solution and potassium iodide solution
  6. observe and record what happens to the potassium chloride solution and potassium iodide solution
  7. repeat step 1
  8. using a pipette, add some iodine water to the potassium chloride solution and the potassium bromide solution
  9. observe and record what happens to the potassium chloride solution and potassium bromide solution
Test tubes containing potassium chloride, potassium bromide and potassium iodide. Each tube has a pipette above it containing chlorine water.

1. Chlorine water is added to three solutions

A halogen cannot displace itself from a solution of one of its salts, eg potassium bromine would not displace bromine water, so these combinations are not done.

Results

Record your observations in a table:

Potassium chloride solutionPotassium bromide solutionPotassium iodide solutionNumber of reactions
ChlorineNot doneSolution darkensSolution darkens2
BromineNo visible reactionNot doneSolution darkens1
IodineNo visible reactionNo visible reactionNot done0
First tube – No reaction: contains chlorine, potassium chloride. Second tube – Displacement: contains bromine, potassium chloride. Third tube – Displacement: contains iodine, potassium chloride.

1. The result of adding chlorine to the three solutions

Analysis

Chlorine could displace bromine and iodine, bromine could only displace iodine, but iodine could not displace chlorine or bromine.

So the order of reactivity is: chlorine > bromine > iodine.

Hazards, risks and precautions

Evaluate the hazards and the precautions needed to reduce the risk of harm. For example:

HazardPossible harmPossible precaution
Chlorine solutionChlorine gas is produced, which is toxic if inhaled.Make sure the lab is well ventilated and avoid inhaling the gas.
Bromine solutionToxic bromine vapour is produced. Solution irritates the skin.Make sure the lab is well ventilated and avoid inhaling the vapour. Wear gloves.
Iodine solutionHarmful to the skin. Stains clothes.Wear gloves. Avoid contact with clothing.
Question

Explain whether chlorine will react with sodium fluoride solution.

Chlorine is less reactive than fluorine, so it would not displace fluorine from sodium fluoride solution.

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