Topic 4: Group 2

Question 1

Reactions with Oxygen

Answer 1

• More vigorous down the group
• Bright flame
• White solid formed
• Barium most reactive

Question 2

Reactions with Chlorine

Answer 2

• More vigorous down the group
• Products are chlorides containing M2+ and Cl- ions

Question 3

Reactions with Water

Answer 3

• Magnesium reacts v slowly
• More vigorous down the group
  Products:
  1. Hydrogen gas
  2. hydroxides

Question 4

Oxides with water

Answer 4

Form colourless solutions
Form hydroxide ions

Question 5

Trend in solubility of hydroxides

Answer 5

Solubility increases down the group.

Question 6

Trend in solubility of sulphates

Answer 6

Solubility decreases down the group.

Question 7

Test for sulphate ions

Answer 7

Add barium chloride/nitrate
Sulphate ions react to form a white precipitate of Barium sulphate.

Question 8

Thermal decomposition of nitrates produce…

Question 9

Trend in thermal stability of carbonates and nitrates

Answer 9

• More thermally stable as you go down group because:
  1. Ionic radius increases down group
  2. charge density decreases
  3. large ions have less polarising ability on carbonate/nitrate ion
  4. more energy is needed to break the C-O / N-O bond.

Question 10

Equation for G2 carbonates and heat

Answer 10

MCO3 –> MO + CO2

Question 11

Equation for G2 nitrates and heat

Answer 11

M(NO3)2 –> 2MO + 4NO2 + O2

Question 12

What is NO2

Answer 12

Brown gas

Question 13

How to do a flame test?

Answer 13

1. Dip nichrome wire in c. HCl
2. Then into the compound to be tested
3. Hold in blue part of flame

Question 14

What is the c.HCl used for?

Question 15

What causes the flame test?

Answer 15

1. Electrons in the metal ions are excited to higher electronic energy levels.
2. As the electrons return to the ground state, the energy is emitted as visible light.
3. The light emitted is characteristic of that metal as each metal has energy levels with different energy gaps between them.

Question 16

What colour does Magnesium burn?

Answer 16

No colour

Question 17

What colour does Potassium burn?

Answer 17

Lilac

Question 17

What colour does lithium burn?

Answer 17

Crimson

Question 18

What colour does sodium burn?

Answer 18

Yellow

Question 19

What colour does beryllium burn?

Answer 19

No colour

Question 20

What colour does calcium burn?

Answer 20

Brick red

Question 21

What colour does strontium burn?

Answer 21

Red

Question 22

What colour does barium burn?

Answer 22

Green

Question 23

Problems with flame test?

Answer 23

1. Compounds often contain sodium compounds as impurities
2. Describing colours with words is subjective