Advanced Inorganic & Organic Chemistry Core Practicals (Edexcel A Level Chemistry)

Exam Questions

21 mins2 questions
1a7 marks

Compound C is a pink crystalline solid containing two cations and one anion.

Three tests were carried out on C. The observation made for each test was recorded in the table.

i)
Complete the statements in the inference column by writing the names or formulae of the species.

(6)

Test Observation Inference
Test 1
Aqueous sodium hydroxide was added to solid C and the mixture warmed
The gas evolved was tested with damp red litmus paper
The red litmus paper turned blue The gas evolved was
....................
One of the cations in C is
....................

Test 2
Concentrated hydrochloric acid was added to an aqueous solution of C

The pink solution turned blue

The other cation in C is
....................
The formula of the complex ion in the blue solution is

....................

Test 3
Dilute hydrochloric acid and aqueous barium chloride were added to an aqueous solution of C
A white precipitate formed

The white precipitate is
....................
The anion in C is

....................

ii)
Use the results of the tests in (a)(i) to give a formula of C.
Do not include water of crystallisation.

(1)

1b1 mark

Write the ionic equation for the reaction between the cation in C and sodium hydroxide producing the gas in Test 1.

State symbols are not required.

1c1 mark

State the type of reaction occurring in Test 2.

1d1 mark

Give a reason why dilute hydrochloric acid is needed in Test 3.

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2a6 marks

Tests are carried out on aqueous solutions of two salts, X and Y.

X contains one cation and one anion.

The observations for each test are recorded in the table.

i)
Complete the table by writing the names or formulae of the species.

(2)

Test Observation Inference
Test 1
Add aqueous sodium hydroxide to an aqueous solution of X
A green precipitate forms
The precipitate turns brown on the top after a few minutes

The cation in X is ..............................

Test 2
To an aqueous solution of X, add dilute hydrochloric acid followed by aqueous barium chloride
A white precipitate forms

The anion in X is ..............................

ii)
Write the ionic equation for the reaction between the cation in X and aqueous sodium hydroxide in Test 1. Include state symbols.

(2)

iii)
Give a reason why the green precipitate turns brown on the top after a few minutes.

(1)

iv)
Give a reason why dilute hydrochloric acid is needed in Test 2.

(1)

2b5 marks

Y contains one cation and one anion.

The observations for each test are recorded in the table.

i)

Complete the table by writing the names or formulae of the species.

(2)

Test Observation Inference
Test 3
Add dilute aqueous ammonia to an aqueous solution of Y until it is present in excess
A pale blue precipitate forms
The precipitate dissolves in excess
ammonia to form a deep blue solution
The cation in Y is ..............................
Test 4
To an aqueous solution of Y, add dilute nitric acid followed by aqueous silver nitrate
A white precipitate forms

The anion in Y is ..............................

ii)
Give the formula of the complex ion present in the deep blue solution at the end of Test 3.

(1)

iii)
Give a reagent that could be added to the mixture at the end of Test 4 to confirm the identity of the anion in Y.
Include the observation when this reagent is added.

(2)

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