2.2.4 Uses of Group 2 Elements

Question 1

3 different uses of calcium compounds :

Answer 1

• Agriculture all 3
• Construction
• Iron Extraction

Question 1

What are the 3 types of calcium compounds?

Answer 1

Limestone (impure CaCO3)
Quicklime (CaO, thermal decomposition of CaCO3)
Slaked lime (Ca(OH)2 when water added to quicklime)

Question 2

How is calcium used in agriculture?

Answer 2

• Limestone, Quicklime and Slaked lime are used to raise pH of soil, neutralising growing acidic conditions of soil

Calcium carbonate most commonly used because its cheaper and safer to handle, but because its largely insoluble it acts slower than Ca(OH)2

Question 3

Uses of Barium

Answer 3

• Medicine, BaSO4
• Barium meal/swallow containing BaSO4 given to patient needing X-ray on intestines
• Barium absorbs X rays so gut shows up white on the image
• Barium is toxic, but BaSO4 is insoluble so not absorbed into blood
• BaCL2 can be used to test for sulphate ions
• White precipitate of BaSO4 is a positive result

Question 4

Uses of Magnesium

Answer 4

Mg(OH)2 used to neutralise excess stomach acid and to treat constipation (partially soluble in water)

Mg(OH)2 (s) + 2HCl (aq) → MgCl2 (aq) + 2H2O (l)

Safe because only partially soluble so makes solution partly alkaline

USED TO EXTRACT TITANIUM FROM TICL4 BY REDUCTION

TiCl4 (g) + 2Mg (l) → Ti (s) + 2MgCl2 (l)

Question 5

How can CaO or CaCO3 be used?

Answer 5

• To remove SO2 from flue gases