Reducing Power Of Hallide Ions

Question 1

What is meant by the reducing power ?

Answer 1

The ability of an atom to donate electrons

Question 2

State the pattern of reducing power of halogens ?

Answer 2

Reducing power increases going down group 7

Question 3

Why does reducing power increase going down the group ?

Answer 3

Ions get larger going down the group
The nucleus attracts more electrons
The larger the ion the further the outer electron is from the nucleus and therefore more shielded from the electrostatic attraction of the nucleus
So weaker electrostatic attraction
And it is easier to lose electrons

Question 4

How do you prove the pattern in reducing ability of the halogens ?

Answer 4

Reacting the ions with concentrated sulfuric acid

Question 5

State the process of reacting hallide ions with concentrated sulfuric acid ?

Answer 5

Take a solid sample of the hallide ion and add sulfuric acid
You produce hydrogen sulphate and a hydrogen hallide as a biproduct

Question 6

This reactions is not a … ?

Answer 6

Redox reaction as sulphur has not changed its oxidation state

Question 7

What does the sulfuric acid act as ?

Answer 7

Acts as an acid that donates a proton to hallide ion

Question 8

What is another observation of this reaction ?

Answer 8

Misty white fumes are produced in all reactions
Proves the presence of this hydrogen hallide

Question 9

What would you expect to see for NaCl and why ?

Answer 9

Only misty white fumes forming
Because chloride is not able to reduce sulfur as it is a very poor reducing agent

Question 10

What happens to hallide ions in general in these reactions ?

Answer 10

The hallide ions become oxidised and lose electrons to form their elements
2X - -> X2 + 2e-

Question 11

What is the observation when NaBr reacts with concentrated sulphuric acid ?

Answer 11

Orange fumes / vapour is produced
And misty fumes
Sulphur dioxide gas is also produced ( choking fumes)

Question 12

How to test if sulphur dioxide was formed ?

Answer 12

Hold filter paper soaked in potassium dichromate over the beaker
Colour change from orange to green is a positive result

Question 13

Half equation for producing sulphur dioxide ?

Answer 13

(SO4) 2- + 4H+. + 2e- –> SO2 + 2H2O

Question 14

What kind of reducing agent is NaI ?

Answer 14

It is a very strong reducing agent

Question 15

What is produced when solid iodide reacts with concentrated sulphuric acid ?

Answer 15

Misty fumes produced
Sulphur dioxide
Iodine produced could produce the grey solid or purple vapour/ gas
Produces solid sulfur and hydrogen sulfide that smells of bad eggs

Question 16

What is iodide able to do in terms of reducing ?

Answer 16

It is able to reduce the sulfur to make solid sulfur which is a yellow solid

Question 17

End