3.1.2 Group 2

Question 1

what are group 2 metals called

Answer 1

alkali earth metals

Question 2

group 2 reaction with oxygen
eg Mg + O2

Answer 2

Oxide = 2MgO

with a 2 infront of the Mg in reactants

Question 3

group 2 reaction with water
eg. Ca + H2O

Answer 3

hydroxide + hydrogen = Ca(OH)2 + hydrogen

Question 4

group 2 reaction with acid
eg Mg + H2SO4

Answer 4

Salt + hydrogen = MgSO4 + H2

Question 5

what happens to reactivity as you move down group 2

Answer 5

reactivity increases - it becomes easier for the atoms to lose 2 electrons

Question 6

what happens to solubility of metal hydroxides as you go down group 2

Answer 6

The solubility of metal hydroxides increase

Question 7

what affect does solubility of the metal hydroxide have on the pH of a solution

Answer 7

Metal hydroxides produce alkaline solutions.
The more soluble the metal hydroxide the more alkaline the solution (the higher the pH)

Question 8

what are the uses of group 2 metal hydroxides compounds

Ca(OH)2, Mg(OH)2, CaCO3

Answer 8

Ca(OH)2 is used by farmers to neutralise acidic soil
Mg(OH)2 and CaCO3 are used as antacids

Question 9

what is the most common reaction on group 2 metals

Answer 9

Redox reactions

Question 10

describe a redox reaction using a group 2 metal

general no specific example

Answer 10

Each metal atom is oxidised, losing 2 electrons to form a 2+ ion with the electron configuration of a nobel gas.
Another species will gain these 2 electrons and be reduced
The group 2 element is called a reducing agent becuase it has reduced another species

Question 11

what trend are seen as you go down group 2 hydroxides

Answer 11

Solubility increases
pH increases
alkalinity increases

Question 12

How do you prove the trend described going down group 2 hydroxides

Solubility, alkalinity and pH increase

Answer 12

1. add a spatula of each group 2 oxide to water in a test tube
2. shake the mixture. On this scale, there is insufficient water to dissolve all the metal hydroxide that forms. You will have a saturated solution of each metal hydroxide with some white solid undissolved at the bottom of the test tube.
3. Measure the pH of each solution. The alkalinity will be seen to increase down the group.

Question 13

describe the use of group 2 compounds as bases

Answer 13

The group 2 oxides, hydroxides and carbonates have many uses related to their basic properties and ability to neutralise acids.
They are often used in agriculture and medicine

Question 14

How are group 2 compounds used in agriculture

Answer 14

calcium hydroxide is added to feilds as lime by farmers to increase teh pH of acidic soils.

Question 15

How are group 2 compounds used in medicine

Answer 15

group 2 bases are often used as antacids for treating acid indigestion
eg. magnesium and aclcuim carbonates
but magnesium hydroxide is also used ( milk of magnesia)