Inorganic 1: Group 2

Question 1

write an equation for the first ionisation energy of magnesium

Answer 1

Mg (g) —> Mg+ (g) + e-

Question 2

what happens to the first ionisation energy as you go down group 2?

Answer 2

decreases

• number of filled electron shells increases down the group
• increased shielding, increased atomic radius
• weaker force between outer electron and nucleus
• less energy needed to remove electron

Question 3

how does reactivity with water change as you go down group 2?

Answer 3

increases (Mg least –> Ba most)

outer electrons further from nucleus and more electron shielding, so electrons are lost more easily

Question 4

write an equation for the reaction of barium and water

Answer 4

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

Question 5

write an equation for the reaction of magnesium and steam

Answer 5

Mg (s) + H2O (g) –> MgO (s) + H2 (g)

Question 6

what is the trend in hydroxide solubility down group 2?

Answer 6

• increases down the group
• Mg(OH)2 is almost insoluble
• Ba(OH)2 creates a strong alkaline solution

Question 7

what is the trend in sulphate solubility down group 2?

Answer 7

• decreases down group
• MgSO4 is soluble
• BaSO4 is insoluble

Question 8

what is the trend in melting point down group 2?

Answer 8

• decreases down group
• because sea of delocalised electrons is further from the positive charge of the nucleus – weaker metallic bonds / forces of attraction which take less energy to weaken

Question 9

what is the trend in atomic radius down group 2?

Answer 9

increases as there are more occupied electron shells down the group

Question 10

write the equations for the extraction of titanium using magnesium

Answer 10

TiO2 + 2Cl2 + C –> TiCl4 + CO2

TiCl4 (l) + 2Mg (s) –> 2MgCl2 (s) + Ti (s)

Question 11

what are flue gases?

Answer 11

gases produced by power stations which are harmful to the environment

Question 12

how can CaO or CaCO3 be used to remove flue gases?

Answer 12

CaCo3(s) + SO2(g) –> CasO3(s) + CO2(g)

CaO(s) + SO2(g) –> CaSO3(3)

Question 13

what is Ca(OH)2 used for and write an equation related to one of its uses

Answer 13

Used to neutralise soil

Ca(OH)2( aq) + 2HCl (aq) –> 2H2O (l) + CaCl2 (aq)

Question 14

what is Mg(OH)2 used for?

Answer 14

milk of magnesia - antacid to treat indigestion and heartburn

Question 15

what is a use of BaSO4 and why is it safe?

Answer 15

in barium meals to outline gut in x-rays

Ba2+ is toxic but is fine as barium sulphate is insoluble

Question 16

how can BaCl2 be used to test for sulfate ions?

Answer 16

add to sample with HCl, white ppt will form if sulfate ions present
Ba^2+ + SO4^2- –> BaSO4