[🧪] Group 2

Question 1

General equation for…

…reaction of Group 2 element with oxygen

Answer 1

2X(s) + O₂(g) → 2XO(s)

Question 2

General equation for…

…reaction of Group 2 elements with water

Answer 2

X(s) + 2H₂O(l) → X(OH)₂(s) + H₂(g)

Mg does not follow this. Instead, it forms MgO(s) and H₂(g)

Question 3

General equation for…

…reaction of Group 2 element with dilute hydrochloric acid (HCl)

Answer 3

X(s) + 2HCl(aq) → XCl₂ (aq) + H₂(g)

Question 4

Describe visual observations when

magnesium reacts with oxygen

Answer 4

burns easily with a bright white flame

Question 5

Describe visual observations when

calcium reacts with oxygen

Answer 5

calcium ignites with difficulty and with a red flame

Question 6

Describe visual observations when

strontium reacts with oxygen

Answer 6

strontium ignites with difficulty with a red flame

Question 7

Describe visual observations when

barium reacts with oxygen

Answer 7

barium ignites with difficulty with a green flame

Question 8

Describe visual observations when

magnesium reacts with water

Answer 8

WITH STEAM: vigorous reaction
WITH WATER: very slow reaction

forms MgO(s) and H₂(g), not a hydroxide

Question 9

Describe visual observations when

calcium reacts with water

Answer 9

reacts moderately

Question 10

Describe visual observations when

strontium reacts with water

Answer 10

reacts rapidly

Question 11

Describe visual observations when

barium reacts with water

Answer 11

reacts vigorously

Question 12

Suggest one visual observation common to all elements of Group 2 when reacted with dilute HCl

Answer 12

They all react vigorously

Question 13

Describe visual observations when

magnesium reacts with dilute H₂SO₄

Answer 13

reacts vigorously

Question 14

Describe visual observations when

calcium reacts with dilute H₂SO₄

Answer 14

reaction is slow because of a sparingly soluble calcium sulfate layer, which coats the metal surface and stops hydrogen bubbles from rising

Question 15

Describe visual observations when

strontium reacts with dilute H₂SO₄

Answer 15

Reaction is quickly stopped by the formation of an insoluble sulfate layer on the metal surface

Question 16

Describe visual observations when

barium reacts with dilute H₂SO₄

Answer 16

Reaction is quickly stopped by the formation of an insoluble sulfate layer on the metal surface

Question 17

Fun facts about strontium and barium oxides

Answer 17

Sr and Ba form oxides in the formulae XO and XO₂

Question 18

Fun facts about beryllium

Answer 18

• does not react with water
• beryllium oxide is amphoteric

Question 19

Nature (pH) of Group 2 oxides

Answer 19

all basic except Be (amphoteric)

Question 20

Can pH depend on solubility?

Answer 20

Yes, it can.

Eg. Group 2 oxides react with water to form alkaline solutions which generally get more alkaline going down the group
* This happens because the hydroxides that form become more soluble as you move down the group
* more OH– ions dissociate into the solution causing the pH to increase

Question 21

Trend in alkalidity of Group 2 hydroxides

Answer 21

Alkalidity increases as you go down the group

Question 22

Ca(OH)2 (aq) is also known as…

Answer 22

…limewater

Question 23

General equation for

reaction of Group 2 oxides with water

Answer 23

XO(s) + H₂O (l) → X(OH)₂ (aq)

Question 24

Describe visual observations when

calcium oxide reacts with water

Answer 24

A vigorous reaction which releases a lot of energy, causing some of the water to boil off as the solid lump seems to expand and open.

Question 25

Suggest one visual observation common to all elements of Group 2 when reacted with dilute acids

Answer 25

form colourless solutions of metal salts

Question 26

Trend in solubility of Group 2 sulfates

Answer 26

down the group, Group 2 sulfates become more insoluble

CaSO₄ is sparingly soluble, while SrSO₄ and BaSO₄ are completely insoluble