Group 2

Question 1

What is periodicity?

Answer 1

Repeating patterns/trends

Question 2

All the group 2 metals react with water to produce a…

Answer 2

Metal hydroxide and hydrogen

Question 3

Explain the reactivity of group 2 metals as you go down the group:

Answer 3

• The reactivity increases as you go down the group.
• The number of shells increases so the nuclear attraction between the outer electron and the nucleus decreases.
• This makes it easier to lose the electrons (act as reducing agents).

Question 4

Explain how beryllium reacts with water:
State the observation:

Answer 4

No reaction with water

Question 5

Explain the reactivity with water as you go down group 2:

Answer 5

Reactivity increases with water

Question 6

Explain how Mg reacts with water, include equations both with steam and with warm water.
State the observation

Answer 6

Mg + H2O(g) -> MgO(s) + H2(g)
Mg + H2O (l) -> Mg(OH)2 (s) + H2(g)

There is no reaction with cold water.
Reacts with steam to form a white flame and a white powder of MgO
Reacts with warm water to form a white solid of Mg(OH)2

Question 7

Explain how Ca reacts with water
State the observation

Answer 7

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

Fizzes in water to form a white solid that is slightly soluble

Question 8

Explain how Sr reacts with water:
State the observation

Answer 8

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

Bubbles and fizzing to form a colourless solution

Question 9

Explain how Ba reacts with water:
State the observation

Answer 9

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

Bubbles and fizzing to form a colourless solution.

Question 10

The solubility of group 2 hydroxides ….. as you go down the group

Answer 10

INCREASES

Question 11

The solubility of group 2 sulphates …. as you go down the group

Answer 11

DECREASES

Question 12

How can you test for sulphate ions?

Answer 12

• Add a small volume of hydrochloric acid to the sample
• Add barium chloride to the solution
• Record your results, if a white precipitate forms, sulfate ions are present.

Question 13

Why is hydrochloric acid added before the barium chloride solution when testing for sulphate ions?

Answer 13

If there are carbonate ions present in the solution, insoluble white BaCO3 will form, which is the same result as if sulphate ions were present. Therefore, the HCL will react with the carbonate ions to form CO2 and H2O, preventing a false positive.

Sulphuric acid is not used as it contains sulfate ions that could react with the barium ions and provide a false positive.

Question 14

How is BaSO4 used in medicine?

Answer 14

It is used as an imaging/contrast agent.

• Before a patient is sent for an X-Ray, they swallow a drink containing barium sulphate.
• The barium sulphate shows a strong contrast on the X-Ray allowing doctors to study the patient’s digestive system

Question 15

Barium ions are super toxic to humans, why is it still safe to give a patient barium sulphate ions?

Answer 15

Barium sulphate is highly insoluble so it just passes straight through!
It won’t disassociate into ions

Question 16

How is Mg(OH)2 used in medicine?

Answer 16

• It’s used to treat indigestion (e.g. heartburn, acid reflux)
• Indigestion is caused by stomach acid travelling up your oesophagus
• Therefore, as it is basic, it neutralises the stomach acid

Question 17

How is Ca(OH)2 used in agriculture?

Answer 17

• Soil used for growing crops have an optimum pH
• If the soil is too acidic, it is treated with Slaked Lime Ca(OH)2
• It’s a base therefore neutralises the acid and raises the pH of the soil

Question 18

How can we extract titanium using Magnesium?

Answer 18

• Titanium is a low density, strong and corrosion resistant metal.
• Reduction of the ore (TiO2) with C forms TiC, which is brittle
• Extraction by electrolysis does not make it pure enough
• Mg is used to form pure Titanium

Question 19

What are the 2 equations for the extraction of titanium using magnesium?

Answer 19

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

Question 20

Why is this method of Titanium extraction expensive?

Answer 20

• High temperatures (high energy)
• TiCl4 purified by fractional distillation in inert argon atmosphere
• Cost of Mg (made by electrolysis)

Question 21

How does Flue Gas Desulphurisation work?

Answer 21

• The SO2 can be removed with an alkali in a process known as wet scrubbing
• Calcium oxide (Lima CaO) or calcium carbonate (lime CaCO3) are used.
• This chemical is sprayed along with water onto the flue gases.

Question 22

Which equations can take place in flue gas desulphurisation?

Answer 22

CaO + SO2 –> CaSO3
CaCO3 + SO2 –> CaSO3 + CO2