2.2 Group 2

Question 1

What is the trend of reactivity down Group 2 and why?

Answer 1

Increasing Reactivity
Distance between outer electron and nucleus increases, shielding increases
Outer electron is more easily lost

Question 2

What is the reaction for magnesium and cold water?

Answer 2

Mg+ 2H2O —> Mg (OH)2 + H2

Question 3

What is the equation for the reaction between magnesium and steam?

Answer 3

Mg + H2O —> MgO + H2

Question 4

How do melting points change down the group?

Answer 4

Decrease down the group
Atomic radius increases
More shielding
Electrostatic forces weaken

Question 5

How does ionisation energy change down the group?

Answer 5

Atomic radius increases
Shielding increases

Question 6

What is the order of solubility with group 2 hydroxides?

Answer 6

Calcium Hydroxide least soluble
Gets more soluble going down the group

Question 7

What is the order of solubility for group 2 sulfates?

Answer 7

Become less soluble down the group

Question 8

What is the use for BaSO4 in medicine and why?

Answer 8

BaSO4 is insoluble so cannot be absorbed through intestines
Used to X-ray soft tissue of intestines

Question 9

What is the use of Mg(OH)2 in medicine?

Answer 9

Neutralises stomach acid so used for indigestion and doesn’t produce CO2 like calcium carbonate
Insoluble so can take as much as necessary

Question 10

What is the agricultural use for Ca(OH)2?

Answer 10

Slaked lime which neutralises acidic soil which could hinder plant growth

Question 11

What is the industrial use of CaCO3?

Answer 11

Flue gas desulfurisation
CaCO3 + SO2 —> CaSO3 + CO

Question 12

How is titanium obtained through use of magnesium?

Answer 12

TiCl4 + 2Mg —> Ti + 2MgCl2

Question 13

Why is titanium expensive?

Answer 13

• Mg is expensive
• Batch process which is slower and more labour intensive
• Argon needed to reduce moisture in atmosphere
• High temperatures