2.2 Group 2

Question 1

Melting point of group 2 elements

Answer 1

High
- Giant mettalic lattice
- Strong electrostatic forces of attraction
- Lots of energy to break metalic bonds

Question 2

Density of group 2 (relative to group 1)

Answer 2

Higher density
- Group 2 ions are smaller
- Pack closer together

Question 3

Reactivity of group 2 elements

Answer 3

All reactive metals (similar reactions as they have the same number of electrons in their outer shell)

Question 4

Appearance of group 2 compounds

Answer 4

White crystalline ionic solids

Question 5

Trend in atomic radius down group 2

Answer 5

Increases
- Atoms become larger
- More shellls + shielding
- Nuclear attraction to outer electron is less

Question 6

Trend in first ionisation energy down group 2

Answer 6

Decreases
- More main shells + shielding
- Weaker attraction between nucleus and electron being removed

Question 7

Trend in melting point down group 2

Answer 7

Decreases
- Metallic ions get bigger
- Less attraction between ions and delocalised electrons

Question 8

Trend in reactivity down group 2

Answer 8

Increases
- React by losing electrons
- More shells + shielding
- Less nuclear attraction to the 2 outer electrons

Question 9

Use of Magnesium

Answer 9

Extracting Ti from TiCl₄

Question 10

Two reactions used to extract titanium from titanium oxide

Answer 10

React titanium oxide with chlorine and carbon
Reduce titanium chloride with magnesium

Question 11

What makes titanium chloride easy to purify?

Answer 11

It is a liquid (distillation can be used)

Question 12

Why is titanium difficult to extract from ores?

Answer 12

Reduction with carbon cannot be used (forms TiC, a brittle titanium carbide)

Question 13

Trend in solubility down group 2 hydroxides

Answer 13

Increases

Question 14

Solubility of Magnesium hydroxide

Answer 14

Sparingly soluable

Question 15

Solubility of Barium hydroxide

Answer 15

Fully soluable

Question 16

Trend in pH down group 2 hydroxides

Answer 16

Increases

Question 17

Why does pH change down group 2 hydroxides?

Answer 17

Differences in solubility changes the number of hydroxide ions released into a solution

Question 18

pH of Magnesium hydroxide

Answer 18

Around 8

Question 19

pH of Barium hydroxide

Answer 19

Around 13

Question 20

Use of Magnesium hydroxide

Answer 20

As an antacid to neutralise excess stomach acid

Question 21

Use of calcium hydroxide

Answer 21

In agriculture to neutralise acidic soil

Question 22

Trend in solubility down group 2 sulfates

Answer 22

Decreases

Question 23

Solubility of Magnesium sulfate

Answer 23

Fully soluable

Question 24

Solubility of Barium sulfate

Answer 24

Insoluable

Question 25

Solubility of Calcium sulfate

Answer 25

Sparingly soluable

Question 26

Use of Barium sulfate

Answer 26

Used in medicine (Barium meal) as it absorbs x-rays allowing soft tissue to be seen.

Question 27

Why is Barium sulfate used in medicine despite Barium ions being toxic?

Answer 27

It is insoluble so cannot be absorbed into the blood

Question 28

Uses of calcium compounds

Answer 28

To remove sulfur dioxide from flue gas (flue gas desulfurizarion)

Question 29

Reaction of Mg with water

Answer 29

- Cold water: Forms Mg(OH)₂(s) + H₂(g) in a very slow reaction - With steam: Forms MgO(s) + H₂(g) and a bright white light

Question 30

Reaction of Ca with water

Answer 30

- Forms Ca(OH)₂(s) + H₂(g) - Calcium hydroxide is slightly soluble and gives an alkaline solution - White solid is still seen (cold water)

Question 31

Reaction of Sr with water

Answer 31

- Forms Sr(OH)₂(aq) + H₂(g) - Strontium hydroxide forms an alkaline solution - Some white solid is still seen (cold water)

Question 32

Reaction of Ba with water

Answer 32

- Forms Ba(OH)₂(aq) + H₂(g) - Barium hydroxide forms a strongly alkaline solution - No white solid is seen (cold water)

Question 33

Trend in reactivity with water as you go down group 2

Answer 33

Increases

Question 34

Equation for forming titanium(IV) chloride from titanium ore

Answer 34

TiO₂ + 2Cl₂ + 2C --> TiCl₄ + 2CO

Question 35

Equation for reducing titanium(IV) chloride with magnesium

Answer 35

TiCl₄ + 2Mg --> 2MgCl₂ + Ti

Question 36

Test for Mg²⁺(aq) ions

Answer 36

Add aqueous sodium hydroxide, a thick white precipitate will form as Mg(OH)₂ is sparingly soluble

Question 37

Test for Ba²⁺(aq) ions

Answer 37

Add sulfuric acid or aqueous sodium sulfate, a thick white precipitate will form as BaSO₄ is insoluable

Question 38

What can barium salts be used for?

Answer 38

Testing for SO₄²⁻ ions (will form precipitate of BaSO₄ if present)

Question 39

What can magnesium salts be used for?

Answer 39

Testing for OH⁻ ions (will form precipitate of Mg(OH)₂ if present)