A1: Group 2

Question 1

Group 2 redox reactions with oxygen

Answer 1

Forms metal oxides, MO

Question 2

Group two outer electrons configuration

Answer 2

Each has two outer shall electrons, in the outer s sub-shell

Question 3

Group 2 redox with water

Answer 3

Forms an alkaline hydroxide ( general formula = M(OH)2) and H2

Question 4

Group 2 redox with dilute acids

Answer 4

Forms a salt and hydrogen

Question 5

Group two trend in reactivity

Answer 5

As you go down the group atomic radium increases and shielding increases, which decreases nuclear attraction, decreasing first and second ionisation energies, and increasing reactivity

Question 6

Reaction of group 2 oxides and water

Answer 6

CaO(s)+H2O(l)–>Ca2+(aq) + 2OH-(aq)

Question 7

What happens when a solution of a group two oxide and water becomes too saturated?

Answer 7

Any further metal and hydroxide ions will form a solid precipitare, for example Ca(OH)2(s)

Question 8

Solubility and pH of group two hydroxides

Answer 8

Solubility increases down the group, so resulting solutions contain more OH-(aq) ions, and a higher pH

Question 9

What is the approximate pH of Mg(OH)2(s) in solution and why?

Answer 9

Around ten, because it is only slightly soluble in water so has a low OH-(aq) concentration

Question 10

Group 2 experiment to find the trend in solubility and pH

Answer 10

1) Add a spatula of each group 2 oxide to water in test tubes and shake
2) There will be insufficient volume of water to dissolve all of the metal hydroxide that forms, so some undissolved solid will remain
3) Measure the pH of each

Question 11

Uses of Ca(OH)2

Answer 11

In agriculture it is added to fields as lime by farmers, which increases the pH of acidic soils

Question 12

Equation of agricultural use of Ca(OH)2

Answer 12

Ca(OH)2(s)+2H+(aq)–>Ca2+(aq) + 2H20(l)

Question 13

Uses of group two bases in medicine

Answer 13

Used as antacids for treating acid indigestion, Mg(OH)2, Mg and Ca carbonates neutralise HCl