inorganic chemrevise

Question 1

Reactivity of group 2 metals

Answer 1

increases down the group

Question 2

Group 2 reactions
Reactions with oxygen.

Answer 2

burn in oxygen
Mg burns with a bright white flame
MgO appears as a white powder.
2 Mg + O2  2 MgO

Question 3

Group 2 reactions with water

Answer 3

reacts in steam to produce magnesium oxide and hydrogen
bright white flame
MgO appears as a white powder.
Mg(s) + H2O(g)  MgO(s) + H2(g)

Question 4

Mg will also react with warm water

Answer 4

Mg + 2 H2OMg(OH)2 + H2
This is a much slower reaction than the reaction with steam and there is no flame.

Question 5

group 2 metals will react with cold water

Answer 5

increasing vigour down the group to form hydroxides.
fizzing
metal dissolving
calcium a white precipitate

Question 6

Steps in extracting titanium

Answer 6

1. 2.
   3.
   TiO2 (solid) is converted to TiCl4 (liquid) at 900C:
   The TiCl4 is purified by fractional distillation in an argon atmosphere.
   The Ti is extracted by Mg in an argon atmosphere at 500C

TiCl4 + 2Mg  Ti + 2 MgCl2

Question 7

Why titanium is expensive

Answer 7

expensive cost of the magnesium
High temperatures required in both steps

Question 8

whats used to remove so2

Answer 8

Calcium oxide
flue gas desulfurisation
containing basic calcium oxide which reacts with the acidic sulfur dioxide in a neutralisation reaction.
SO2 + CaOCaSO3

Question 9

Magnesium hydroxide

Answer 9

insoluble in water
Mg2+(aq) + 2OH-(aq)Mg(OH)2(s).
eutralise excess acid in the stomach and to treat constipation.

Question 10

Calcium hydroxide

Answer 10

white precipitate It is used in agriculture to neutralise acidic soils.

e limewater turns cloudy as white calcium carbonate is produced.
Ca(OH)2 (aq) + CO2 (g)  CaCO3 (s) + H2O(l)

Question 11

Solubility of sulfates

Answer 11

Group II sulfates become less soluble down the group. BaSO4 is the least soluble.

Question 12

Testing for presence of a sulfate ion

Answer 12

BaCl2 solution acidified with hydrochloric acid is used as a reagent to
test for sulfate ions.

Ba2+ (aq) + SO42-(aq)BaSO4 (s).

Question 13

potassium chlroide with
chlrine
bromine
iodine

Answer 13

Very pale green solution, no reaction
Yellow solution, no reaction
Brown solution, no reaction

Question 14

potassium bromide (aq) with clorine
bromine
iodine

Answer 14

Yellow solution, Cl has displaced Br
Yellow solution, no reaction
Brown solution, no reaction

Question 15

potassium iodide (aq)

Answer 15

Brown solution, Cl has displaced I

Brown Solution, Br has displaced I

Brown Solution, no reaction

Question 16

The reactions of halide ions with silver nitrate

Answer 16

Fluorides produce no precipitate
Chlorides produce a white precipitate Ag+(aq) + Cl- (aq)  AgCl(s)
Bromides produce a cream precipitate Ag+(aq) + Br- (aq)AgBr(s)
Iodides produce a pale yellow precipitate Ag+(aq) + I- (aq) AgI(s)

Question 17

Silver chloride in dilute ammonia

Answer 17

AgCl(s) + 2NH3(aq) [Ag(NH3)2]+ (aq) + Cl- (aq)
Colourless solution

Question 18

silver bromide conc ammonia

Answer 18

to form a
complex ion
AgBr(s) + 2NH3(aq) [Ag(NH3)2]+ (aq) + Br - (aq)
Colourless solution

Question 19

iodine and sulfer

Answer 19

White steamy fumes of HI are evolved. Black solid and purple fumes of Iodine are also evolved
A colourless, acidic gas SO2
A yellow solid of sulfur
H2S (Hydrogen sulfide), a gas with a bad egg smell,

Question 20

Disproportionation

Answer 20

element simultaneously oxidises and reduces.

Question 21

chlrone and water

Answer 21

Cl (g) + HO(l)⇌ HClO(aq) + HCl(aq)

Question 22

chlroine and diulte naoh

Answer 22

Cl2,(and Br2, I2) in aqueous solutions will react with cold sodium hydroxide. The colour of the halogen solution will fade to colourless.
Cl2 (aq) + 2 NaOH (aq)  NaCl (aq) + NaClO (aq) + H2O (l)
The mixture of NaCl and NaClO is used as bleach and to disinfect/ kill bacteria.

Question 23

soodumand cold water

Answer 23

It fizzes around on surface etc. 2Na(s)+2H2O(l)2NaOH(aq)+H2 (g)

Question 24

mag and cold water

Answer 24

Magnesium reacts very slowly with cold water to form the hydroxide but reacts more readily with steam to form the oxide Mg (s) + H2O (g)MgO (s) + H2 (g)

Question 25

period 3 flame colours

Answer 25

Sodium burns with a yellow flame to produce a white solid. Mg, Al, Si and P burn with a white flame to give white solid smoke. S burns with a blue flame

Question 26

ipnic oxide

Answer 26

The metal oxides (Na2O, MgO, Al2O3) are ionic. They have high melting points. They have ionic giant lattice structures: strong forces of attraction between oppositely charged ions : higher mp. They are ionic because of the large electronegativity difference between metal and O The increased charge on the cation makes the ionic forces stronger (bigger lattice enthalpies of dissociation) going from Na to Al so leading to increasing melting points. Al2O3 is ionic but does show some covalent character. This can be explained by the electronegativity difference being less big or alternatively by the small aluminium ion with a high charge being able to get close to the oxide ion and distorting the oxide charge cloud.

Question 27

macromoelcue oxides

Answer 27

SiO2 is macromolecular: It has many very strong covalent bonds between atoms. High energy needed to break the many strong covalent bonds – very high mp +b

Question 28

simple molecular oxides

Answer 28

P4O10 (s), SO2 (g) are simple molecular with weak intermolecular forces between molecules (van der waals + permanent dipoles) so have lower mp’s. They are covalent because of the small electronegativity difference between the non-metal and O atoms. P4O10 is a molecule containing 4P’s and 10 O’s. As it is a bigger molecule and has more electrons than SO2 it will have larger van der waals forces between molecules and a higher melting point.

Question 29

Metal ionic oxides tend to react with water

Answer 29

form hydroxides which are alkaline Na2O (s) + H2O (l)2Na+ (aq) + 2OH- (aq) pH 13 (This is a vigorous exothermic reaction) The ionic oxides are basic because the oxide ions accept protons to become hydroxide ions in this reaction (acting as a Bronsted-Lowry base) MgO (s) + H2O (l)Mg(OH)2 (s) pH 9 Mg(OH)2 is only slightly soluble in water as its lattice is stronger sofewerfreeOH- ionsareproducedandsolowerpH.

Question 30

non-metal, simple molecular, covalent, oxides react with water to give

Answer 30

acids. P4O10 (s) + 6 H2O (l)  4 H3PO4(aq) pH 0 (this is a vigorous exothermic reaction) SO2 (g) + H2O (l) H2SO3 (aq) pH 3 (weak acid) SO2 + H2O H+ + HSO3- SO3 (g) + H2O (l) H2SO4 (aq) pH 0 SO3 + H2O H+ + HSO4

Question 31

Reactions of halides with silver nitrate

Answer 31

Fluorides produce no precipitate Chlorides produce a white precipitate Ag+(aq) + Cl- (aq)  AgCl(s) Bromides produce a cream precipitate Ag+(aq) + Br- (aq)AgBr(s) Iodides produce a pale yellow precipitate Ag+(aq) + I- (aq) AgI(s)