3.2.2- Group 2 Alkaline Earth Metals

Question 1

Trend in atomic radius down group 2

Answer 1

Increase down group

More electrons which go into shells increasingly distant from nucleus

Question 2

Trend in first ionisation energies down group 2

Answer 2

Decrease down group

Each atom contributes 2 electrons to delocalised cloud metallic bonding is weaker due to increase size of ion

Question 3

Trend in melting and boiling point down group 2

Answer 3

Decreases down group
Despite increasing nuclear charge
The values decrease due to extra shielding provided by additional filled energy levels

Question 4

Trend in reaction with water

Answer 4

Be does not react with water

Mg –> Ba
Increasing reaction
Produced hydrogen gas and metal hydroxide

Question 5

Metal hydroxides solubility down group

Answer 5

Be(OH)2 
   |
   |
   | 
Ba(OH)2 

Insoluble to very soluble

Question 6

Why is Mg(OH)2 sparingly soluble

Answer 6

Only a small amount of it dissolves

Question 7

What is the solubility of the group 2 metal sulphates

Answer 7

BeSO4
|
|
BaSO4

BaSO4 is insoluble goes up to BeSO4 which is very soluble

Question 8

Use of Mg(OH)2

And equation

Answer 8

Milk of magnesia which is a suspension of Mg(OH)2
Used to neutralise stomach acid

Mg(OH)2 + 2HCl –> MgCl2 +2H2O

Question 9

Ca(OH)2 uses

Answer 9

Limewater in solution
When CO2 bubbled through goes cloudy

Or

Slaked lime used in agriculture to increase the pH of soil by removing acids

Question 10

MgSO4.7H2O uses

Answer 10

Makes Epsom salts which soothes aching joints and is a muscle relaxant

Question 11

CaSO4. 2H2O uses

Answer 11

Makes gypsum which forms plaster of Paris

Question 12

BaSO4 uses

Answer 12

Makes barium meal lines organs to be seen when x-rayed. Insoluble so does not cross lining into the blood stream

Question 13

Testing for sulphate ions

Answer 13

Add HCl to remove any carbonate ions

Add BaCl2 to test for sulphate ions a white precipitate will be observed

Question 14

Testing for sulphate ion equation of adding HCl to remove carbonate ions

Answer 14

CO3 ^2- (aq) + 2H+( –> CO2 (g) +H2O (l)

Question 15

Test for sulphates ions adding BaCl2

Answer 15

Ba^2+(aq) + SO4(aq) –> BaSO4 (s)

Question 16

Uses of titanium

Answer 16

Hip replacement - used as does not corrode and is less dense than steel

Question 17

Extraction of titanium

Answer 17

1)
TiO2+2Cl2+2C–> TiCl4+2CO
2)
Reduced TiCl4+2Mg –> Ti+2MgCl2

Question 18

What does inert conditions mean

Answer 18

A interactive condition e.g. Add argon otherwise the reactants react with oxygen

Question 19

Why is titanium more expensive than steel

Answer 19

Harder to extract
It is a batch process rather than continuous like blast furnace
Also Mg and Cl2 are used