Group 2 (alkaline earth metals)

Question 1

What happens to atomic radius down group 2?

Answer 1

Increases due to extra electron shells

Question 2

What happens to first ionisation energy down group 2?

Answer 2

Decreases due to increased atomic radius and shielding

Question 3

What happens to melting point down group 2?

Answer 3

Decreases due to weaker metallic bonding. Mg doesn’t fit the pattern (lower than all other group 2 metals)

Question 4

How is magnesium used to extract titanium?

Answer 4

Titanium dioxide is heated with carbon and chlorine, forming titanium chloride and CO. Titanium chloride then reduced by Mg

Question 5

What acts as the reducing agent in the extraction of titanium?

Answer 5

Magnesium

Question 6

What are the formulas for extracting titanium using magnesium?

Answer 6

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

Question 7

Why is using magnesium to extract titanium less efficient?

Answer 7

Happens in two stages

Question 8

Why can’t titanium be extracted using carbon?

Answer 8

Produces a carbide that is too brittle
TiO2 + C –> TiC + O2

Question 9

Equation for the reaction of oxygen and sulfur dioxide?

Answer 9

2SO2 + O2 –> 2SO3

Question 10

Equation for the reaction of sulfur trioxide and water which ultimately produces acid rain?

Answer 10

SO3 + H2O –> H2SO4

Question 11

What is quicklime?

Answer 11

CaO

Question 12

Equation for the use of CaO to prevent acid rain?

Answer 12

CaO + SO2 –> CaSO3 (calcium sulfite)

Question 13

What is limestone?

Answer 13

Calcium Carbonate (CaCO3)

Question 14

Equation for the use of CaCO3 to prevent acid rain?

Answer 14

CaCO3 + SO2 –> CaSO3 + CO2

Question 15

Equation for the reaction with group 2 metals with water (apart from beryllium which is unreactive)?

Answer 15

Ca + 2H2O –> Ca(OH)2 + H2

Question 16

Equation for the reaction with Mg and and steam (vigorous reaction)?

Answer 16

Mg + H2O (g) –> MgO + H2

Question 17

What happens to the solubility of hydroxides in water down group 2?

Answer 17

Increases (except magnesium hydroxide which is sparingly soluble, so is a white ppt)

Question 18

What is used to cure heartburn and why?

Answer 18

Mg(OH)2 because it’s a base just strong enough to neutralise the pH of the stomach, and is sparingly soluble so not strong enough to damage the body

Question 19

How is soil pH neutralised?

Answer 19

Ca(OH)2 (slaked lime)

Ca(OH)2 + 2HCl –> CaCl2 + 2H2O

Question 20

What happens to the solubility of sulfates down group 2?

Answer 20

Decreases (barium sulfate almost insoluble)

Question 21

How and why is barium sulfate used to make tissues visible on x-rays?

Answer 21

Dense enough to absorb x-rays and insoluble enough so not toxic

Question 22

How is barium chloride used to test for sulfate ions?

Answer 22

Will react with sulfate ions to form barium sulfate (white ppt)

Question 23

What if instead of sulfate ions the solution contained carbonate ions?

Answer 23

Would form barium carbonate which is also a white ppt.
So add acid which reacts with carbonate to form CO2 (removes carbonate ions)