1.8 halogens

Question 1

properties of fluorine

Answer 1

yellow
gas at room temp

Question 2

properties of chlorine

Answer 2

pale green
gas at room temp

Question 3

properties of Bromine

Answer 3

red-brown
liquid at room temp

Question 4

properties of Iodine

Answer 4

grey-black
solid at room temp

Question 5

Cl Br I in water

Answer 5

Cl- soluble forming a pale green or colourless solution
Br- soluble forming a yellow or orange or brown solution
I- virtually insoluble but will dissolve in iodide solution forming a brown solution

Question 6

Cl Br I in hexane

Answer 6

Cl- soluble forming a colourless solution
Br- soluble forming a red or brown solution
I- soluble forming a purple solution

Question 7

when do halogens undergo halogen displacement reactions

Answer 7

when reacting with a halide as they are less reactive

Question 8

how does going down the group affect its reducing ability

Answer 8

it increases

Question 9

halide test for Cl Br I in silver nitrate then dilute then conc ammonia

Answer 9

Cl- white yes yes
Br- cream no yes
I- yellow no yes

Question 10

what does sodium fluoride and sulfuric acid produce

Answer 10

sodium sulfide and hydrogen fluoride

Question 11

what does sodium chloride and sulfuric acid produce

Answer 11

sodium sulfide and hydrogen chloride

Question 12

what does sodium bromide and sulfuric acid produce

Answer 12

1. sodium sulfide and hydrogen bromide
2. hydrogen bromide sulfuric acid react to give bromine, sulfur dioxide and water

Question 13

what does sodium iodide and sulfuric acid produce

Answer 13

1. sodium sulfide and hydrogen iodide
2. hydrogen iodide and sulfuric acid react to give iodine, sulfur dioxide and water
3. hydrogen iodide and sulfuric acid react again to give Iodine, sulfur and water
4. hydrogen iodide and sulfuric acid react for a third time to give iodine hydrogen sulfide and water

Question 14

alternative tests for halides other than silver nitrate

Answer 14

1. CL^- gives HCL gas which itself can be tested using a glass rod dipped into conc ammonia solution, white smoke would be given off
2. Br^- gives bromine vapour which can be seen as red-brown fumes
3. I^- gives iodine vapour which can be seen as purple fumes and/or a grey black solid forms

Question 15

advantages of chlorine in water

Answer 15

cheaper than ozone
provides residual protection as it is still present in the water when it reaches the consumer
More soluble in water than ozone

Question 16

disadvantages of chlorine in water

Answer 16

cannot kill some microorganisms
leaves chemicals in the water
Unpleasant taste
Toxic to humans so very low quantities used

Question 17

advantages of ozone in water

Answer 17

kills some different types of microorganisms
breakdown product is oxygen
no residual chemicals in water
no unpleasant taste
removes metal and organic particles from water

Question 18

disadvantages of ozone in water

Answer 18

more expensive than chlorine
does not provide residual protection against microorganisms
less soluble in water than chlorine so requires special mixing techniques