Group 7

Question 1

What happens when the halogens are oxidised with metals?

Answer 1

Reduced to negative halide ions

Question 2

What happens when halogens are oxidised with nonmetals?

Answer 2

Noble gas configuration of often achieved through covalent bonding

Question 3

What are the physical properties of the halogens?

Answer 3

Nonmetallic elements that exist as diatomic molecules
Very reactive and strong oxidising agents
Less reactive as you go down the group
Nonpolar so dissolves in hydrocarbon solvents

Question 4

How does splitting it into aliquots in a titration affect the accuracy of results?

Answer 4

Decreases accuracy

Smaller titration volume so larger percentage error

Question 5

What is the general equation for a reaction between the halogens and sodium hydroxide in a cold dilute alkali?

Answer 5

X2 + 2OH- (aq) –> X-(aq) + XO-(aq) + H2O

Question 6

What is the equation for the decomposition of halate I ions?

Answer 6

3XO- –> 2X-(aq) + XO3-(aq)

Question 7

What does the products of the disproportionation reaction of halogens depend on?

Answer 7

The temperature

All examples of halogens when alkalis are disproportionation reactions

Question 8

What can be observed when the hydrogen halides react with ammonia gas?

Answer 8

White smoke so it can be used to test for a hydrogen halide

Question 9

What is the general equation for the reaction between ammonia gas and hydrogen halides?

Answer 9

NH3 (g) + HX(g) –> NH4X(s)

Question 10

Which is a stronger oxidising agent? Chlorine or iodine?

Answer 10

Chlorine

Question 11

What does concentrated sulphuric acid reacts with the halide to form?

Answer 11

NaCl(s) + H2SO4(l) –> NaHSO4(s) +HCl(g)

Question 12

What does sulphuric acid act as when it reacts with a halide?

Answer 12

Oxidising agent

Question 13

What is produced when sodium bromide and sulphuric acid react?

Answer 13

Br2 H2O SO2

Question 14

What is produced when sodium iodide and sulphuric acid react?

Answer 14

H2S H2O I2

Question 15

What is the test for chloride ions?

Answer 15

Silver nitrate
White precipitate
Soluble in dilute ammonite
Darkens in sunlight

Question 16

What is the test for bromide ions?

Answer 16

Silver nitrate
Cream precipitate
Insoluble in dilute ammonia
Soluble in concentrated ammonia
Darkens in sunlight

Question 17

What is the test for iodide ions?

Answer 17

Silver nitrate
Yellow precipitate
Insoluble in concentrated ammonia

Question 18

Is the ionic equation for the reaction between silver nitrate and chloride?

Answer 18

Ag+ + Cl- –> AgCl(s)

Question 19

If C4H9I is used instead of C4H9Br, the rate of formation of C4H9NH2 increases. Why?

Answer 19

The C-I bond is much weaker than the C-Br bond

Question 20

Why might there be a difference between the students mean titre and the accurate value other than due to limitations in the equipment?

Answer 20

Judgement of colour at endpoint

Adding starch too early

Question 21

How do you determine how many significant figures to calculate an answer to?

Answer 21

Least accurate measurement in the experiment/calculation