Group 2 The Alkaline Earth Metals

Question 1

What is the trend in atomic radius for group 2 + why

Answer 1

As you move down the group the atomic radius increases
Increased number of shells

Question 2

What in the trend of ionisation energies in group 2 + why

Answer 2

Decreases as you move down group 2
There are more shells so further away from the positive nucleus this decreases attraction so less energy to remove outermost electron

Question 3

General tend in melting point of group 2

Answer 3

Decreases as you move down group

Question 4

Why does the melting point decrease as you move down group 2?

Answer 4

Metallic structure —-> positive metal ion and sea of delocalised electrons
As you move down size of atomic radius increases but number of delocalised electrons and charges are the same
Larger distance positive nuclei of metal ion and electrons
Weakens force of attraction less energy to break

Question 5

When group 2 metals react with water are they oxidised or reduced

Answer 5

Oxidised

Question 6

Trend in reactivity of group 2 with water + why

Answer 6

Increases moving down group
Larger atomic radius decreased ionisation energy less energy to lose the outer 2 electrons

Question 7

Group 2 metal + water =

Answer 7

Metal hydroxide + hydrogen

Question 8

General formula of group 2 metal + water

Answer 8

X(s) + 2H2O (l) —> X(OH)2 (aq) + H2 (g)
Must be balanced with state symbols

Question 9

Magnesium + water vs magnesium + steam

Answer 9

Mg (s) + 2H2O (l) —-> Mg(OH)2 (aq) + H2 (g)
VS
Mg (s) + H2O (g) —> MgO (aq) +H2 (g)

Question 10

Rate of reaction with water group 2 trend

Answer 10

Increases moving down group 2

Question 11

How is titanium extracted

Answer 11

1) Titanium ore TiO2 is converted to Titanium chloride TiCl4 by heating with carbon and chlorine gas
2) pass TiCl4 through fractional distillation column to purify
3) purified TiCl4 is reduced using magnesium in 1000 degrees furnace

Question 12

Equation for reduction of titanium chloride with magnesium

Answer 12

TiCl4 + 2Mg —-> Ti + 2MgCl2

Question 13

Solubility of group 2 hydroxides trend

Answer 13

Increases going down the group

Question 14

Solubility of group 2 sulphates trend

Answer 14

Decreases moving down the group

Question 15

Uses of Mg(OH)2

Answer 15

Used for indigestion tablets because it neutralises stomach acids. AKA it’s a antacid

Question 16

How soluble is Mg(OH)2

Answer 16

Sparingly

Question 17

Uses of Ca(OH)2

Answer 17

Used in agriculture to neutralise acidic soils

Question 18

How do you remove sulphur dioxide from flue gases

Answer 18

Web scrubbing
Alkali used to neutralise SO2 in flue gases
1) dissolve CaO or CaCO3 in water
2) spray on sulphur dioxide gas

Question 19

Equation for web scrubbing

Answer 19

CaO(s) + 2H2O (l) + SO2 (g) —> CaSO3(s) + 2H2O (l)
CaCO3 (s) + 2H2O (l) + SO2 (g) —-> CaSO3 (s) + 2H2O (l) + CO2 (g)

Question 20

Solubility of group 2 sulfates

Answer 20

Decreases going down group 2

Question 21

Test for sulphate ions

Answer 21

1) add hydrochloric or nitric acid
2) add barium chloride
White precipitate - positive
Nothing - negative

Question 22

Why do we need to add hydrochloric acid or nitric acid first for sulfates ion test

Answer 22

To remove carbonate ions ( by reacting to produce CO2)
Otherwise barium carbonate will form which is a white precipitate which is false positive

Question 23

Uses of Barium sulphate in medicine

Answer 23

It is insoluble so does not enter blood stream
Patient give BaSO4 to eat because it absorbs X-rays. Dr can see digestive system

Question 24

Ionic equation barium chloride + solution with sulfate ions

Answer 24

Ba+2 (aq) + SO4 2- (aq) —> BaSO4

Question 25

Two difference reaction of magnesium with water and reaction magnesium with steam x3

Answer 25

Slower water vs faster steam
Magnesium hydroxide vs magnesium oxide
Bubbling of water vs bright white light

Question 26

Reaction magnesium and calcium with sulfate

Answer 26

Magnesium sulfate soluble and calcium sulfate insoluble
Calcium sulfate coast the surface of the calcium
Coating prevents further contact with acid etc

Question 27

Define rate of reaction

Answer 27

Amount of substance formed in unit time

Question 28

Why does doubling reactant increases rate of reaction

Answer 28

Twice as many particles
Twice as many successful collisions