Group 2 - inorganic I

Question 1

Write an equation for the first ionisation energy of magnesium

Answer 1

Mg (g) → Mg+ (g) + e-

Question 2

Explain why this graph is this shape:
check google

Answer 2

First Ionisation energy increases across group 3 because of increased nuclear charge, decreased atomic radius and same electron shielding means more energy is needs to remove the first electron.
Dips at Al because: outer electron is in a 3p orbital, higher energy than 3s orbital → less energy needed to remove electron
Dips at S because one 3p orbital contains two electrons → repulsion between paired electrons → less energy needed to remove one

Question 3

What happens to the first ionisation energy as you go down group 2? Why?

Answer 3

Decreases because: number of filled electron shells increases down the group → increased shielding, increased atomic radius → weaker force between outer electron and nucleus → less energy needed to remove electron

Question 4

How does reactivity with water change as you go down group 2?

Answer 4

Increases (Mg least → Ba most)
Because outer electrons further from nucleus and more electron shielding, so electrons are lost more easily

Question 5

Write an equation for the reaction of Barium and water

Answer 5

Ba (s) + 2H2O (l) → Ba(OH)2 (aq) + H2 (g)

Question 6

Write an equation for the reaction of Magnesium and steam.

Answer 6

Mg (s) + H2O (g) → MgO (s) + H2 (g)

Question 7

What is the trend in hydroxide solubility down group 2?

Answer 7

Increases down the group
Mg(OH)2 is almost insoluble
Ba(OH)2 creates a strong alkaline solution

Question 8

What is the trend in sulphate solubility down group 2?

Answer 8

Decreases down group
MgSO4 is soluble
BaSO4 is insoluble

Question 9

What is the trend in melting point down group 2? Why?

Answer 9

Decreases down group
Because sea of delocalised electrons is further from the positive charge of the nucleus → weaker metallic bonds / forces of attraction which
take less energy to weaken

Question 10

What is the trend in atomic radius down group 2?

Answer 10

Increases as there are more occupied electron shells down the group

Question 11

Write the equations for the extraction of Titanium using Magnesium.

Answer 11

TiO2 + 2Cl2 + C → TiCl4 + CO2
TiCl4 (l) + 2Mg (s) → 2MgCl2 (s) + Ti (s)

Question 12

What are flue gases?

Answer 12

Gases produced by power stations which are harmful to the environment

Question 13

What is Ca(OH)2 used for? Write an equation related to one of its uses

Answer 13

Used to neutralise soil
Ca(OH)2 (aq) +2HCl (aq) → 2H2O (l) + CaCl2 (aq)

Question 14

How can CaO or CaCO3 be used to remove flue gases? Write equations

Answer 14

CaCO3 (s) + SO2 (g) → CaSO3 (s) + CO2 (g) CaO (s) + SO2 (g) → CaSO3 (s)

Question 15

What is Mg(OH)2 used for?

Answer 15

Milk of magnesia - antacid to treat indigestion, heartburn, wind etc.

Question 16

What is a use of BaSO4?
Why is this safe?

Answer 16

In barium meals to outline gut in X-rays
Ba2+ is toxic but is fine as barium sulphate is insoluble

Question 17

How can BaCl2 be used to test for sulfate ions?

Answer 17

Add your sample with HCl first to acidify the solution, then add BaCl2. White precipitate will form if sulfate ions are present.
Ba2+ + SO 2- -> BaSO 44