Chemistry CCEA AS Level 1.8 (Group VII - The Halogens)

What state is fluorine at room temperature?

Yellow gas

What state is chlorine at room temperature?

Pale green gas

What state is bromine at room temperature?

Red-brown liquid

What state is iodine at room temperature?

Grey-black solid

What is the solubility of chlorine in water?

Soluble forming a pale green/colourless solution

What is the solubility of bromine in water?

Soluble forming orange/yellow/brown solution

What is the solubility of iodine in water?

Virtually insoluble but will dissolve in iodide solution forming a brown solid

What is the solubility of chlorine in hexane?

Soluble forming colourless solution

What is the solubility of bromine in hexane?

Soluble forming red solution

What is the solubility of iodine in hexane?

Soluble forming purple solution

What does chlorine form with cold aqueous sodium hydroxide?

- Sodium Chloride

- Sodium Chlorate (I)

- Water

What does chlorine form with hot concentrated sodium hydroxide?

- Sodium Chloride

- Sodium Chlorate (V)

- Water

What does chlorine form with water?

- Hydrochloric acid

- Chloric (I) acid/Hypochlorous acid

What do solid metal halides form with concentrated sulphuric acid/concentrated phosphoric acid?

The corresponding hydrogen halide gas

What is observed in a reaction between fluorine and sulphuric acid?

- Misty fumes (HF)

- Heat released

- Gas produced

- Solid disappears

- Pungent smell (HF)

What is observed in a reaction between chlorine and sulphuric acid?

- Misty fumes (HCl)

- Heat released

- Gas produced

- Solid disappears

- Pungent smell (HCl)

What is observed in a reaction between bromine and sulphuric acid?

- Misty fumes (HBr)

- Heat released

- Gas produced

- Solid disappears

- Red-brown vapour (Br2)

- Pungent smell (HBr/SO2/Br2)

What is observed in a reaction between iodine and sulphuric acid?

- Misty fumes (HI)

- Heat released

- Gas produced

- Solid disappears

- Purple vapour and grey-black solid (I2)

- Pungent smell (HI/SO2/I2)

- Rotten egg smell (H2S)

- Yellow solid (S)

How do you test for Cl^- ions?

Gives off HCl gas which can be tested with a glass rod dipped in concentrated ammonia solution (white smoke given off)

How do you test for Br^- ions?

Gives off bromine vapour (red-brown fumes)

How do you test for I^- ions?

Gives of iodine vapour (purple fumes/grey-black solid)

What are the advantages of adding chlorine to drinking water?

- Cheaper than ozone

- Provides residual protection

- More soluble in water than ozone

What are the disadvantages of adding chlorine to drinking water?

- Cannot kill some microorganisms

- Leaves chemicals in water

- Unpleasant taste

- Toxic to humans

What are the advantages of adding ozone to drinking water?

- Kills more microorganisms

- Breakdown produces oxygen

- No residual chemicals

- No unpleasant taste

- Removes metal/organic particles

What are the disadvantages of adding ozone to drinking water?

- More expensive than chlorine

- No residual protection

- Less water soluble than chlorine