Group 7 - the Halogens

Name the colour and physical state (at rtp) of F₂

Name the colour and physical state (at rtp) of Cl₂

Name the colour and physical state (at rtp) of Br₂

Name the colour and physical state (at rtp) of I₂

Describe and explain the trend in boiling points as you go down Group 7

Complete the sentences:
A substance is said to be ___________ if it has a low boiling points. So you could say that ___________ decreases down the group

In terms of electron transfer, what happens when halogen atoms react?

Give the general formula for the reduction of halogen atoms

TRUE OR FALSE:
Halogens are oxidising agents

Describe and explain the trend in reactivity down Group 7

Complete the sentences:
More reactive halogens will oxidise and _________ the halide ions of less reactive halogens. Reactivity ____________ down the group and so a halogen will displace a halide from solution if the halide is _______ it in the periodic table

Which of the halide ions (Br⁻ and/or I⁻) does chlorine displace?

Which of the halide ions (Cl⁻ and/or I⁻) does bromine displace?

Which of the halide ions (Br⁻ and/or Cl⁻) does iodine displace?

Chlorine displaces bromide (Br⁻). Give the ionic equation for this displacement reaction

Chlorine displaces iodide (I⁻). Give the ionic equation for this displacement reaction

Bromine displaces iodide (I⁻). Give the ionic equation for this displacement reaction

What is the colour of iodine water (I₂)?

What is the colour of bromine water (Br₂)?

What is the colour of chlorine water (Cl₂)?

When displacement reactions happen, there are colour changes. However, orange and brown can sometimes look similar. What can be done to make the changes easier to see?

What is the colour of the solvent layer when iodine is dissolved in an organic solvent (e.g. hexane)?

What is the colour of the solvent layer when bromine is dissolved in an organic solvent (e.g. hexane)?

What is the colour of the solvent layer when chlorine is dissolved in an organic solvent (e.g. hexane)?

Describe the observations made when chlorine water reacts with potassium bromide solution

Describe the observations made when chlorine water reacts with potassium iodide solution

Describe the observations made when bromine water reacts with potassium chloride solution

Describe the observations made when bromine water reacts with potassium iodide solution

Describe the observations made when iodine water reacts with potassium chloride solution

Describe the observations made when iodine water reacts with potassium bromide solution

Apart from using displacement reactions, what test could be used to identify halides?

Outline the method for the silver nitrate test, including the product formed (and the general ionic equation) if the test is positive

What are the different colours of the precipitate formed when a silver nitrate test is done on chloride, bromide and iodide ions?

It isn't always easy to tell the difference between the precipitates. What can be added to tell the halides apart?

In the silver nitrate test, why is dilute nitric acid added to the solutions?

Outline the method of adding dilute/concentrated ammonia to the precipitates formed by the silver nitrate test

Dilute ammonia is added to Cl⁻, Br⁻ and I⁻ solutions. What observations are made?

Concentrated ammonia is added to Br⁻ and I⁻ solutions. What observations are made?

TRUE OR FALSE:
The larger the ion is, the more difficult it is to dissolve in ammonia