The solubility of group 2 hydroxides is given in the table below. Calculate the mass of calcium hydroxide that will dissolve in 50 g of water at 298 K . Group 2 hydroxides Solubility at 298 K ( mol / 100 g of water) Mg ( OH ) 2 2 . 0 × 10 - 5 Ca ( OH ) 2 1 . 5 × 10 - 3 Sr ( OH ) 2 3 . 4 × 10 - 3 Ba ( OH ) 2 1 . 5 × 10 - 2

From the given table, the solubility of calcium hydroxide at 298 K is 1 . 5 × 10 - 3 mol per 100 g of water. The molar mass of calcium hydroxide ( Ca ( OH ) 2 ) is = 40 + 2 16 + 1 = 74 g mol - 1 Therefore, mass dissolved in 100 g of water = 1 . 5 × 10 - 3 × 74 = 0 . 111 g And, the mass dissolved in 50 g of water = 0 . 111 2 = 0 . 0555 g

EASY

AS and A Level

IMPORTANT

Earn 100

Predict the pH of the solution formed on the reaction of barium with water.

Important Questions on Group 2

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 11 - Group 2>BEFORE YOU START>Q 1

Which one of the following electronic configurations correctly describes an atom of calcium?

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 11 - Group 2>Question>Q 3

Radium (

Ra

) is a radioactive element found below barium at the bottom of Group 2. Applying your knowledge of Group 2, discuss and predict with a partner what you would expect to see if you mixed radium hydroxide solution with dilute sulfuric acid.

MEDIUM

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 11 - Group 2>Question>Q 3

The solubility of group 2 hydroxides is given in the table below. Calculate the mass of calcium hydroxide that will dissolve in $50 g$ of water at $298 K$ .

Group 2 hydroxides	Solubility at $298 K$ ( $mol / 100 g$ of water)
$Mg {(OH)}_{2}$	$2.0 \times 10^{- 5}$
$Ca {(OH)}_{2}$	$1.5 \times 10^{- 3}$
$Sr {(OH)}_{2}$	$3.4 \times 10^{- 3}$
$Ba {(OH)}_{2}$	$1.5 \times 10^{- 2}$

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 11 - Group 2>EXAM-STYLE QUESTIONS>Q 2

Beryllium is a Group 2 element. Write the electronic configuration of beryllium.

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 11 - Group 2>EXAM-STYLE QUESTIONS>Q 2

Beryllium is a Group 2 element. Using dot-and-cross diagrams, and showing the outer electrons only, draw the electronic configurations of beryllium and oxygen before and after bonding.

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 11 - Group 2>EXAM-STYLE QUESTIONS>Q 4

For the following reaction, state which element is oxidised and which is reduced, and give the changes in oxidation number.

$Sr + {Cl}_{2} \to {SrCl}_{2}$

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 11 - Group 2>EXAM-STYLE QUESTIONS>Q 4

For the following reaction, state which element is oxidised and which is reduced, and give the changes in oxidation number.

$Sr + 2 H_{2} O \to Sr {(OH)}_{2} + H_{2}$

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 11 - Group 2>EXAM-STYLE QUESTIONS>Q 4

For the following reaction, state which element is oxidised and which is reduced, and give the changes in oxidation number.

$2 Mg + {CO}_{2} \to 2 MgO + C$

Predict the pH of the solution formed on the reaction of barium with water.

Important Questions on Group 2

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