Inorganic Chemistry

Question 1

Group 2 reactions with water

Answer 1

M(s) + 2H2O(l) -> M(OH)2(aq) + H2(g)

Increase in reactivity going down the group

Question 2

Solubility of Group 2 hydroxides

Answer 2

Increase in solubility going down the group

Question 3

Solubility of Group 2 sulfates

Answer 3

Decrease in solubility going down the group

Question 4

Test for sulfate ions

Answer 4

Solution acidified with nitric or hydrochloric acid (to remove carbonate ions)
Barium chloride solution is added under test
A white precipitate of barium sulfate will form if sulfate ions present

Question 5

Magnesium hydroxide

Answer 5

An antacid

Question 6

Calcium hydroxide

Answer 6

Neutralise acidic soil

Question 7

Magnesium sulfate

Answer 7

A laxative

Question 8

Calcium sulfate

Answer 8

Plaster casts

Question 9

Barium sulfate

Answer 9

Contrast medium for x-rays

Question 10

Barium carbonate

Answer 10

Rat poison

Question 11

Extraction of titanium

Answer 11

TiO2 + 2C + 2Cl2 -> TiCl4 + 2CO
TiCl4 + Mg -> 2MgCl2 + Ti
Batch process, high temperature, argon atmosphere

Question 12

The Halogens

Answer 12

F2: yellow gas, Cl2: green gas, Br2: brown liquid, I2: black solid

Question 13

Trend in bond energy of Group 7

Answer 13

Bond energy decreases down the group

However fluorine F-F bonds are unexpectedly weak

Question 14

Oxidising ability of Group 7

Answer 14

Oxidising ability decreases going down the group

More electrostatic attraction and less shielding so easier to gain electrons

Question 15

Reducing ability of Group 7

Answer 15

Reducing ability increases going down the group

Easier to lose electrons

Question 16

Sodium chloride + conc sulphuric acid

Answer 16

NaCl + H2SO4 -> NaHSO4 + HCl

Acid-base reaction

Question 17

Sodium bromide + conc sulphuric acid

Answer 17

2H+ + 2Br- + H2SO4 -> SO2 + 2H2O + Br2

Question 18

Sodium iodide + conc sulphuric acid

Answer 18

H2SO4 + 6H+ + 6I- -> 3I2 + S + 4H2O

H2SO4 + 8H+ + 8I- -> 4I2 + H2S + 4H2O

Question 19

Test for halides

Answer 19

Add dilute nitric acid to the sample to remove any soluble carbonate or hydroxide ions
Add a few drops of silver nitrate solution

Question 20

Result for halides test

Answer 20

Fluoride- no precipitate
Chloride- white precipitate (dissolves in dilute ammonia)
Bromide- cream precipitate (dissolves in conc ammonia)
Iodide- yellow precipitate (insoluble in conc ammonia)

Question 21

Chlorine + water

Answer 21

Cl2 + H2O -> HClO + HCl

Question 22

Chlorine + water in sunlight

Answer 22

2Cl2 + 2H2O -> 4HCl + O2

Question 23

Sodium chlorate + water

Answer 23

NaClO + H2O -> Na+ + OH- + HClO

Question 24

Chlorine + sodium hydroxide

Answer 24

Cl2 + 2NaOH -> NaClO + NaCl + H2O