Halogens Flashcards Preview

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Flashcards in Halogens Deck (23):
1

Fluorine

Pale yellow gas

2

Chlorine

Pale green gas

3

Bromine

Dark red liquid

4

Iodine

Grey solid

5

Fluorine in non-polar solvents and water

Reacts

6

Chlorine in non-polar solvents and water

Pale green solution

7

Bromine in non-polar solvents and water

Orange solution

8

Iodine in non-polar solvents

Purple solution

9

Iodine in water

Insoluble but brown solution if excess KI

10

Why do the melting and boiling points of the halogens increase steadily down the group?

This is due to the increase in strength of the Van Der Waal's forces between the molecules, which results from the increasing number of electrons in the molecule and the increasing surface area of the molecule.

11

Electronegativity

The ability of an atom to attract electrons in a covalent bond.

12

Why does electronegativity of the halogen atoms decreases down a group?

As the number of shells increases, the shielding increases and the electrons in the covalent bond are further from (and more shielded from) the nucleus. Therefore they are less strongly attracted to the nucleus and the electronegativity decreases.

13

NaCl + H2SO4

HCl, NaHSO4
White fumes of HCl will be seen. The fumes will turn blue litmus paper red.

14

NaBr + H2SO4

Br2, H2O, SO2, NaHSO4
White fumes will be seen which turn blue litmus paper red. The red/orange colour of bromine will also be seen.

15

NaI + H2SO4

I2, H2O, S, H2S, NaHSO4
White fumes will be seen which turn blue litmus paper red. The purple colour of iodine vapour will also be seen and there a will be a smell of rotten eggs due to the presence of H2S.

16

Why is nitric acid added to silver nitrate solution?

Ensure that any carbonate or hydroxide ions, often found as impurities with halide ions, are removed as CO2 or water and so do not interfere with the precipitate.

17

Ammonia + AgCl

Dissolves

18

Ammonia + AgBr

If dilute ammonia is added to AgBr(s), there is no reaction but if concentrated ammonia is added then the precipitate dissolves.

19

Ammonia+ AgI

Does not dissolve either in dilute or in concentrated ammonia.

20

Cl2(g) + H2O(l)

HCl(aq) + HClO(aq)

21

Why is chlorine used for sterilisation?

It is a mild oxidising agent and effective at killing bacteria without being harmful to humans. Chlorine is toxic to humans in anything other than very small doses, so care must be taken not to over-chlorinate the water supply.

22

Cl2(g) + 2OH-(aq)

Cl-(aq) + OCl-(aq) + H2O(l)

23

What is ClO used for?

It is an important oxidising agent and is the active ingredient in domestic bleach, NaClO.