CL 8- group 2

Question 1

Ca and O₂

reaction and observations

Answer 1

2Ca + O₂ –> 2CaO

bright red flame, white powder

Question 2

Ca and H₂O

reaction and observations

Answer 2

Ca + 2H₂O –> Ca(OH)₂ + H₂

bubbles of gas produced, water turns cloudy

Question 3

Ca and HCL

reaction and observations

Answer 3

Ca + 2HCL –> CaCl₂ + H₂

Ca dissolves, bubbles of gas produced

Question 4

reactivity trend down group 2

Answer 4

• increases
• IE decreases because
• atomic radius and shielding increases
• attraction between nucleus and outer shell decreases, easier to lose electrons

Question 5

solubility of group 2 oxides

trend and pH prediction

Answer 5

oxides become more soluble as you go down the group
expect resulting solutions to be alkaline and so have pH of 11-14 ( as more OH- ions given off)

Question 6

MgCO₃ and heat

reaction and name/trend

Answer 6

produces MgO + CO₂
called thermal decomposition
carbonates become more difficult to decompose as you go down the group, more energy needed

Question 7

Mg(OH)₂

uses of group 2 metals

Answer 7

Milk of Magnesia contains Mg(OH)₂, used to relieve acid indigestion as Mg(OH)₂ neutralises excess stomach acid

Question 8

Ca(OH)₂

uses of group 2 metals

Answer 8

Ca(OH)₂ spread on fields by farmers, reduces soil acidity by neutralising the acid in the soil

Question 9

group 2 sulfates solubility

trend

Answer 9

decreases as you go down the group until BaSO₄, which is completely insoluble

Question 10

use of BaSO₄

Answer 10

used in ‘barium meal’ in x-ray imaging to view the digestive system
is toxic but insoluble so not absorbed