2.2 Group 2 - Alkaline Earth Metals

Question 1

Describe the two stages of extracting titanium from its ore.

Answer 1

→ titanium dioxide is heated with carbon & chlorine, forming titanium chloride
→ titanium is reduced by magnesium, forming magnesium chloride & pure titanium

Question 2

Explain why the usual method of extracting metals does not work for titanium

Answer 2

• heating titanium dioxide with carbon produces a carbide
• this is too brittle to be useful as an engineering material

Question 3

Write the equation for the reaction between magnesium and steam.

Answer 3

Mg (s) + H₂O (g) → MgO (s) + H₂ (g)

Question 4

Write an ionic equation, with state symbols, to show the reaction of calcium with an excess of water.

Answer 4

Ca (s) + 2H₂O (l) → Ca²⁺ (aq) + 2OH⁻ (aq) + H₂ (g)

Question 5

State the role of water in the reaction with calcium.

Answer 5

oxidising agent

Question 6

State a use of magnesium hydroxide in medicine.

Answer 6

neutralises stomach acid (antacid)

Question 7

From Mg(OH)₂ to Ba(OH)₂, the solubility in water…

Answer 7

increases

Question 8

From Mg to Ba, the first ionisation energy…

Answer 8

decreases

Question 9

From Mg to Ba, the atomic radius…

Answer 9

increases

Question 10

Write the simplest ionic equation for reaction between acidified barium chloride & a solution containing sulfate ions.

Answer 10

Ba²⁺ + SO₄²⁻ → BaSO₄

Question 11

Explain why acid should be added before barium chloride when testing for sulphate ions.

Answer 11

to remove any carbonate ions because:
→ they react with barium chloride to form barium carbonate
→ barium carbonate will precipitate to give a false positive test for sulphate ions

Question 12

State why sulfuric acid should not be used to acidify barium chloride.

Answer 12

• sulfuric acid contains sulphate ion
• which reacts with barium chloride to form white precipitate
• (false positive)

Question 13

Suggest why magnesium chloride wouldn’t be a suitable test for sulphate ions.

Answer 13

• magnesium chloride would react with sulphate ions to form magnesium sulphate
• magnesium sulphate is soluble
• will not form a precipitate to give any indication of a positive result

Question 14

In the extraction of strontium from SrO, what role does aluminium have?

Answer 14

• gains oxygen therefore reducing agent

Question 15

Explain why the precipitate of silver chloride is washed several times with deionised water.

Answer 15

to remove soluble impurities
to remove excess silver nitrate

Question 16

Other than cost, explain one advantage of using magnesium hydroxide rather than magnesium carbonate to reduce acidity in the stomach.

Answer 16

does not produce CO₂

Question 17

Magnesium ribbon reacts with hot water. Heated magnesium ribbon reacts with steam. State two differences between these reactions.

Answer 17

• faster with steam
• hot water produces hydroxide
• steam produces oxide

Question 18

From MgSO₄ to BaSO₄, the solubility in water…

Answer 18

decreases

Question 19

What is observed when testing for sulphate ions using barium ions?

Answer 19

white precipitate is formed

Question 20

State one use of barium sulfate in medicine and why.

Answer 20

• barium meals
• insoluble therefore not toxic

Question 21

Suggest one major reason why extracting strontium using aluminium is expensive.

Answer 21

aluminium is extracted using electrolysis

Question 22

Write the equation for the reaction between magnesium and titanium(IV) chloride.

Answer 22

TiCl₄ + 2Mg → 2MgCl₂ + Ti

Question 23

Outline the practical steps that you would take to determine the solubility of calcium hydroxide in this solution.

Answer 23

→ take a known volume of saturated solution
→ evaporate the filtrate until dry
→ weigh the residue

Question 24

Equations to remove Sulfur Dioxide from flue gases

Answer 24

CaO + 2H₂O + SO₂ → CaSO₃ + 2H₂O
CaCO₃ + 2H₂O + SO₂ → CaSO₃ + 2H₂O + CO₂