C9

Question 1

What is the trend in atomic radius in group 2?

Answer 1

Increase, as each atom going down the group will have an additional electron shell, therefore will have greater shielding which will result in a weaker efa between the valence shell and nucleus meaning it is pulled towards the nucleus less

Question 2

What is the trend in reactivity down the group 2?

Answer 2

It will increase as you go down the group, each atom will have 1 more electron shell, meaning that each atom has more shielding, resulting in a weaker efa between the nucleus and valence shell, meaning the electron is easier to lose therefore will have an increased reactivity.

Question 3

What is the trend in ionisation energy in group 2?

Answer 3

Decreases as you go down the group because each atom will have plus 1 electron shells, therefore will have more shielding which means the efa between the nucleus and valence electron is weaker, meaning it will require less energy to ionise.

Question 4

What is the trend in melting point in group 2?

Answer 4

Decreases down the group because as you go down the group atomic radius increases, meaning in the metallic structure, the larger ions will have to act over a longer distance which will weaken the efa between the positive ions and sea of delocalised electrons.

Question 5

What type of reaction is a group 2 metal + water?

Answer 5

Redox

Question 6

What is formed when a group 2 metal reacts with LIQUID water?

Answer 6

An Alkaline solution (metal hydroxide) and hydrogen (H2) gas

Question 7

What is the balanced symbol reaction for a group 2 metal with LIQUID water, e.g. Mg

Answer 7

Mg + 2H2O —–> Mg(OH)2 + H2

Question 8

What is Mg(OH)2 commonly used for?

Answer 8

Used in milk of magnesia for treating indigestion as it neutralises stomach acid

Question 9

What is true about the rate of reaction of a group 2 metal with liquid water?

Answer 9

Reacts very slowly

Question 10

What is formed when a group 2 metal reacts with STEAM?

Answer 10

A metal oxide (that is a white soluble solid) and hydrogen gas

Question 11

What is true about the rate of reaction of a group 2 metal with liquid water?

Answer 11

Reacts very fast as the steam provides it with extra energy,

Question 12

What is the balanced symbol reaction of a group 2 metal with STEAM?

Answer 12

Mg + H2O —-> MgO + H2

Question 13

What is the common use of Ca(OH)2 in agriculture?

Answer 13

Called Slaked Lime and is used to treat acidic soil, it is used to treat acidic soil.

Question 14

How and why is titanium extracted?

Answer 14

1. TiO2 (solid) is converted to TiCl4 (liquid) at 900C:
2. The TiCl4 is purified by fractional distillation in an argon atmosphere.
3. The Ti is extracted by Mg from the TiCl4 in an argon atmosphere at 500C through the following reaction:

TiCl4 + 2Mg –> 2MgCl2 + Ti

Question 15

Why cant Titanium be extracted with Carbon?

Answer 15

As it will form TiC which makes the metal brittle

Question 16

What is CaO used for?

Answer 16

It is used to remove S02 from flue gases (factory pollutants) to stop it being released into the atmosphere:
CaO + 2H2O + SO2 —> CaSO3 + 2H2O

Question 17

What is the trend in solubility of the group 2 metal hydroxides?

Answer 17

Increase down the group. (Mg(OH)2 is least)

Question 18

How soluble is Magnesium hydroxide?

Answer 18

Almost insoluble

Question 19

How soluble is Calcium hydroxide?

Answer 19

Sparingly Soluble

Question 20

How soluble is Strontium Hydroxide?

Answer 20

More Soluble

Question 21

How soluble is Barium Hydroxide?

Answer 21

Dissolves to produce a very alkaline solution:

Ba(OH)2 + aq —-> Ba2+ 2OH-

Question 22

What is the trend in solubility of the group 2 sulfates?

Answer 22

Decrease down the group (Mg(OH2) the most)

Question 23

What are the 2 uses of Barium Sulfate?

Answer 23

• As its sulfate is really insoluble, it is used as a medical tracer, that allows internal organs to be imaged.
• It is also used as a test for sulfate ions. The solution is first acidified with HNO3 or HCL to remove any carbonate ions as CO2, This has to be done as BaCO3 also produces a white precipitate. After that a barium chloride solution is then added and if it forms a white precipitate, it will contain sulphate ions:
  Ba2+ + SO4- —–> BaSO4(s)

Question 24

What would you observer from the group 2 metals reacting with water?

Answer 24

• Fizzing (more vigorous down group)
• The metal will dissolve (faster down the group)
• The solution will heat up (more down the group)

Question 25

Mg Flame Colour

Answer 25

White

Question 26

Ca Flame Colour

Answer 26

Orange/Red

Question 27

Sr Flame Colour

Answer 27

Scarlet

Question 28

Ba Flame Colour

Answer 28

Green

Question 29

Colour of Mg(OH)2

Answer 29

White

Question 30

Why is the extraction of titanium expensive?

Answer 30

• Mg is expensive
• Argon in the argon atmosphere is expensive (this step is important to remove moisture as TiCl4 is susceptible to hydrolysis
• High temp is required
• Batch process

Question 31

Why does an Mg ribbon need to be cleaned off before it reacts?

Answer 31

An Mg ribbon will often have a thin layer of MgO on the outside, this needs to be cleaned off using emery paper as when testing for rates of reaction with an uncleaned ribbon, you will get a false result as both the Mg and MgO will be reacting at different rates.