4: Inorganic Chemistry

Question 1

Trend in ionisation energies down group 2

Answer 1

Ionisation energies decrease

Question 2

Reason for group 2 trend in ionisation energies

Answer 2

The atomic radius increases and the shielding increases

Question 3

Trend in reactivity down group 2

Answer 3

Metals become more reactive down group 2

Question 4

Combustion of group 2 metals (excluding barium)

Answer 4

2M + O2 → 2MO

Question 5

Combustion of barium

Answer 5

Ba + O2 → BaO2

Question 6

Reaction of group 2 metals with water (except magnesium and beryllium)

Answer 6

M + 2 H2O → M(OH)2 + H2

Question 7

Reaction of magnesium and steam

Answer 7

Mg + H2O → MgO + H2

Question 8

Reaction of metals and chlorine

Answer 8

M + Cl2 → MCl2

Question 9

Reaction of group 2 metal oxides with water (excluding beryllium oxide)

Answer 9

MO + H20 → M(OH)2

Question 10

General reaction of acid and base

Answer 10

Acid + Base → Salt + Water

Question 11

Trend in solubility of group 2 sulphates

Answer 11

Solubility decreases down the group

Question 12

Group 2 sulphates with their solubility

Answer 12

Magnesium - Soluble
Calcium - Slightly soluble
Strontium - Insoluble
Barium - Insoluble

Question 13

Trend in solubility of group 2 hydroxides

Answer 13

Solubility increases down the group

Question 14

Group 2 hydroxides with their solubility

Answer 14

Magnesium - Insoluble
Calcium - Soluble
Strontium - Soluble
Barium - Soluble

Question 15

Trend in thermal stability of carbonates

Answer 15

Thermal stability increases down the groups

Question 16

Reason for trend in thermal stability of carbonates

Answer 16

• As the cations become larger, the charge density becomes less, so they distort the anion less
• This distortion weakens the C-O bond

Question 17

Reason for group 1 carbonates being more stable than group 2

Answer 17

The charge on the cation is less

Question 18

Nitrate thermal stability

Answer 18

-All nitrates thermally decompose

Question 19

Group 1 nitrates thermal decomposition (excluding lithium nitrate)

Answer 19

2 MNO3 → 2 MNO2 + O2

Question 20

Group 2 nitrates thermal decomposition

Answer 20

2 M(NO3)2 → 2 MO + 4 NO2 + O2

Question 21

Lithium nitrate thermal decomposition

Answer 21

4 LiNO3 → 2 Li2O + 4NO2 + O2

Question 22

Explanation of flame colours in flame tests

Answer 22

• When group 1 or 2 metals or their compounds are placed in a flame, the electrons are pushed to a higher energy level
• As the electrons drop back down they give out energy as light

Question 23

How to show the trend of thermal decomposition in carbonates

Answer 23

• Pass the gas produced through limewater

- Record how long it takes to turn cloudy

Question 24

Appearance of Fluorine

Answer 24

RTP - yellow gas

Question 25

Appearance of Chlorine

Answer 25

RTP - pale green gas Aq - colourless Org - colourless

Question 26

Appearance of Bromine

Answer 26

RTP - brown liquid Aq - yellow/orange Org - orange

Question 27

Appearance of Iodine

Answer 27

RTP - grey solid Aq - brown Org - Purple

Question 28

Trend in MP/BP of halogens

Answer 28

MP/BP increase down the group as there are more electrons, and therefore stronger London forces

Question 29

Trend in electronegativity of halogens

Answer 29

Electronegativity decreases down the group and atomic radius increases and more shielding

Question 30

Trend in reactivity of halogens

Answer 30

Reactivity decreases down the group as the attraction of the nucleus decreases as there is more shielding

Question 31

How to show trend in reactivity in halogens

Answer 31

Can be shown by the displacement in the reaction of a halogen with a Group 1 metal halide (e.g Cl2 + 2KBr → Br2 + 2KCl)

Question 32

Reaction of a halogen with a metal

Answer 32

2 M + X2 → 2 MX

Question 33

Chlorine reaction with water

Answer 33

Cl2 + H20 ⇌ HCl + HClO

Question 34

Use of reacting chlorine with water

Answer 34

HClO sterilises water, and is in small quantities as the reaction is reversible

Question 35

Chlorine reaction with cold NaOH

Answer 35

Cl2 + NaOH → NaClO + NaCl

Question 36

Chlorine reaction with hot NaOH

Answer 36

3 Cl2 + 6 NaOH → NaClO3 + 5 NaCl

Question 37

Formula of bleach

Answer 37

NaClO

Question 38

Reaction of Fe(II) with halides

Answer 38

Fluorine, Chlorine and Bromine are strong enough to oxidise F2 + 2 Fe(II) → 2 F- + 2 Fe(III)

Question 39

Reaction of Group 1 halides with concentrated sulphuric acid

Answer 39

MX + H2SO4 → MHSO4 + HX

Question 40

Addition reaction following Group 1 halides reaction with conc. H2SO4

Answer 40

Only with bromide/iodide: 2 HX + H2SO4 → X2 + 2 H20 + SO2

Question 41

Trend in strength as reducing agent in halides

Answer 41

As the halide ions become bigger they become more able to lose an electron and therefore become stronger

Question 42

Dissolving and dissociation of hydrogen halides in water

Answer 42

HX → H+ + X-

Question 43

Reaction of hydrogen halides and gaseous ammonia

Answer 43

HX + NH3 → NH4X

Question 44

Observation in reaction of hydrogen halides and gaseous ammonia

Answer 44

Dense white smoke produced