Group 2 Properties

Question 1

Which Group 2 Ions Have a WHITE PRECIPITATE in OH-

Answer 1

Mg2+

Ca2+

Question 2

Which Group 2 Ions have a WHITE PRECIPITATE in SO4 2-

Answer 2

Sr2+

Ba2+

Question 3

Trend in Atomic Radius for group 2

Answer 3

radius increases down the group

more shells of electrons

Question 4

Trend in melting point down group 2

Answer 4

melting point decreases down the group
metallic bonding weakens
distance between positive ions and delocalised electrons increases
FoA decrease

Question 5

Trend in first ionisation energy down group 2

Answer 5

decreases down the group
more shielding 
further from nucleus
lower FoA
less energy to remove electron

Question 6

Trend in reactivity down group 2

Answer 6

reactivity increases down the group

Question 7

Group 2 reaction with oxygen using Mg as example

Answer 7

Mg burns with a bright white flame
Produces a metal oxide (MgO) which is a white ionic solid with a high MP

Layer of metal oxide coating the outside must be removed with emery paper before reaction with magnesium ribbon

Question 8

Magnesium reaction with steam

Answer 8

Produces magnesium oxide and hydrogen

Burns with a bright white flame

Question 9

Magnesium reaction with warm water

Answer 9

produces magnesium hydroxide Mg(OH)2 and hydrogen

Slow reaction without a flame

Question 10

Group 2 metal reaction with cold water

Answer 10

Reacts vigorously
Forms metal hydroxides EG) X(OH)2
and hydrogen

Question 11

Observations for group 2 metal reaction with cold water

Answer 11

Fizzing (More vigorous down group)
Dissolving (More vigorous down group)
Solution heating up (More down group)
A white precipitate appearing with calcium (Less precipitate down group)

Question 12

What do the metal hydroxides do to the water’s pH

Answer 12

Make it alkaline (If they’re water soluble)

Question 13

Steps in extracting titanium with magnesium

Answer 13

1) TiO2 converted to TiCl2 (900 degrees c)
TiO2 + 2Cl2 +2C= TiCl4 + 2CO
2) TiCl2 purified through fractional distillation
3) Ti extracted with Mg in argon atmosphere at 500 degrees
TiCl4 + 2Mg = Ti + 2MgCl2

Question 14

Magnesium Hydroxide

Answer 14

Insoluble in water
Mg2+ + 2OH- = Mg(OH)2
pH 9 = slightly dissolved OH-
Mg(OH)2 used in medicine to neutralise excess stomach acids
Mg(OH)2  +2HCl = MgCl2 + 2H2O

Question 15

Calcium Hydroxide

Answer 15

Partially in soluble
Ca2+ + 2OH- = Ca(OH)2
pH 11= more OH- ions dissolved
Used to test for CO2
Ca(OH)2 + CO2 = CaCO3 + H2O

Question 16

Barium Hydroxide

Answer 16

Fully Soluble
Ba2+ + 2OH- = Ba(OH)2
Strongly alkaline
Ba(OH)2 + aq = Ba2+ + 2OH-

Question 17

Trend in solubility of sulphates in group 2

Answer 17

solubility decreases down the group

Question 18

Trend in solubility of group 2 hydroxides

Answer 18

solubility increases down the group

Question 19

Sulphate ion

Answer 19

SO4 2-

Question 20

Where is barium sulphate used

Answer 20

X ray of intestines

low solubility stops it from being absorbed into bloodstream

Question 21

How is BaCl2 used to test for sulphate ions

Answer 21

BaCl2 solution acidified with HCl used as a reagent
Barium sulphate is made (White precipitate)
Ba2+ + SO4 2- = BaSO4

Question 22

Why is barium sulphate acidified with HCl

Answer 22

Salts often have carbonate impurities, barium carbonate also has a white precipitate so it can be confused for sulphate.
HCl reacts with CO3
Fizzing due to CO2 product