Inorganic Chemistry And The Periodic Table

Question 1

Group 2 + oxygen
General equation

Answer 1

Solid white oxide
2M(s) +O2(g)—-> 2MO(s)

Question 2

Group 2 + chlorine
General equation

Answer 2

Solid white chlorides
M(s) + Cl2(g)——-> MCl2(s)

Question 3

Group 2 + water
General equation

Answer 3

Metal hydroxide + hydrogen
M(s) + 2H2O(l) —-> M(OH)2 (aq) + H2(g)

Question 4

Group 2 oxide + water
General equation

Answer 4

Hydroxides
MO(s) + H2O(l)—-> M(OH)2 (aq)

Question 5

Group 2 oxide+ dilute acid
General equation

Answer 5

Salt+water
MO(s)+2HCl(aq)—-> MCl2(aq)+H2O(l)

Question 6

Group 2 hydroxide + dilute acid
General equation

Answer 6

M(OH)2(aq)+2HCl(aq)—-> MCl2(aq)+2H2O(l)

Question 7

Solubility trend group 2 hydroxides

Answer 7

Increases down the group
Solutions more strongly alkaline

Question 8

Solubility trend group 2 sulfates

Answer 8

Decreases down the group

Question 9

Trend in thermal stability down the group for G2 carbonates and nitrates

Answer 9

Increases
Polarising power of the cation decreases down the group as the ionic radius increases and so more shielding (lower charge density)
Less distortion of carbonate/ nitrate anion
Weakens the CO/ NO bond less

Question 10

Thermal stability of G2 vsG1 nitrates/ carbonates

Answer 10

G2 carbonates/ nitrates are less thermally stable
The greater the charge on the cation, the greater the distortion and the less stable to anion becomes
2+ vs 1+

Question 11

Thermal decomposition of G1 carbonates

Answer 11

Thermally stable (until higher temperatures)
Exception: Li2CO3 which decomposes to Li2O and CO2

Question 12

Thermal decomposition of G2 carbonates

Answer 12

Form oxide and carbon dioxide
MCO3 (s)—-> MO(s) + CO2 (g)

Question 13

Thermal decomposition of G1 nitrates

Answer 13

Forms nitrite and oxygen
2MNO3(s)——>2MNO2(s)+O2(g)
Exception:
LiNO3 which decomposes to form Li2O, NO2, O2

Question 14

thermal decomposition of G2 nitrates

Answer 14

Forms oxide, nitrogen dioxide, oxygen
2M(NO2)2(s)——>2MO(s)+4NO2(g)+O2(g)

Question 15

Testing the thermal stability of nitrates

Answer 15

How long it takes for a certain amount of oxygen to be produced (enough to relight a glowing splint)
How long it takes for an amount of brown gas (NO2) to be produced (in a fume cupboard)

Question 16

Testing thermal stability of carbonates

Answer 16

How long it takes for an amount of carbon dioxide to be produced, use limewater

Question 17

Limewater

Answer 17

Saturated solution of calcium hydroxide)

Question 18

Formation of characteristic flame colours

Answer 18

Energy absorbed from the flams causes electrons to be promoted to higher energy levels, excitation. Electrons de excite and move back down to ground state, releasing energy in the form of light.
The difference in energy between the higher and lower energy levels determines the wavelength of light released and so the colour of light

Question 19

Flame colours for:
Lithium, sodium, potassium, rubidium, caesium, calcium, strontium and barium

Answer 19

Red, orange/ yellow, lilac, red, blue, brick-red, crimson, green

Question 20

States and colours of the halogens

Answer 20

F- pale yellow gas
Cl- green gas
Br- red/brown liquid
I- grey solid

Question 21

Colour change when halogen displaces halide in aqueous solution

Answer 21

Cl displaces Br- yellow/ orange
Cl or Br displaces I- brown

Question 22

Coloured layers of displaced halide after addition of an organic solvent

Answer 22

Bromine- orange/red
Iodine- pink/ violet
Chlorine is virtually colourless

Question 23

Hypochlorous acid (HClO)

Answer 23

Ionises to make chlorate (1) ions
HClO+H2O——>ClO-+H3O+
ClO- kill bacteria

Question 24

Disproportionation reaction of chlorine with cold, dilute aqueous sodium hydroxide to form bleach

Answer 24

Produces NaOX+NaX+H2O

Question 25

Disproportionation reaction of chlorine with hot alkali

Answer 25

Produces NaXO3+5NaX+3H2O

Question 26

Trend in reducing power of halides down the group

Answer 26

Increases Because ions get bigger and there’s more shielding (outer electron more easily lost)

Question 27

Reaction of KF or KCl with H2SO4

Answer 27

KCl(s)+H2SO4(l)—->KHSO4(s)+HCl(g) Misty fumes Reaction stops here Not redox Chlorine not strong enough reducing reagent to reduce the sulfur further

Question 28

Reaction of KBr with H2SO4

Answer 28

KBr+H2SO4—>KHSO4+HBr misty fumes 2HBr(aq)+H2SO4(l)——>Br2(g)+SO2(g)+2H2O(l) Redox Sulfur oxidation state changes from +6 to +4 Br2 orange fumes

Question 29

Reaction of KI with H2SO4

Answer 29

KI+H2SO4—>KHSO4+HI 2HI(g)+H2SO4—->I2(g)+SO2+2H2O 6HI(g)+SO2(g)—->H2S(g)+3I2(s)+@H2O(l) +6 to +4 then +4 to -2

Question 30

Reaction of hydrogen halides with ammonia and with water to produce acids

Answer 30

HX can dissolve in water to produce misty fumes of acidic gas (turn damp blue litmus paper red) HX react with ammonia gas to produce white fumes NH3(g)+HCl(g)——>NH4Cl(s)

Question 31

reaction of aqueous Cl-, Br- and I- with aqueous silver nitrate solution, followed by aqueous ammonia solution

Answer 31

+dilute nitric acid to remove ions +silver nitrate solution AgF soluble so no precipitate AgCl- white + ammonia solution- precipitate dissolves to give colourless solution AgBr- cream + ammonia solution- unchanged with dilute, dissolves in concentrated to form colourless solution AgI- yellow + ammonia solution- does not dissolve (precipitate remains)

Question 32

Test for sulfates

Answer 32

+dilute HCl (removes carbonate ions) +barium chloride solution White precipitate of barium sulfate forms

Question 33

Test for ammonium ions

Answer 33

+NaOH Gently heat Ammonia gas given off is alkaline so will dissolve in the water on damp red litmus paper and turn it blue

Question 34

Equation for testing for ammonium ions

Answer 34

NH4Cl(aq)+NaOH(aq)—-> NH3(g)+H2O(l)+NaCl(aq)

Question 35

Explain how the trend in reactivity of group 2 elements is determined by their electronic configurations

Answer 35

Outer electron further from nucleus More shielding So first ionisation energy decreases down group so reactivity increases