OCR Gateway GCSE Chemistry

Topic Questions

GCSEChemistryOCR GatewayTopic Questions4. Predicting & Identifying Reactions & Products4.2 Identifying the Products of Chemical Reactions

4.2 Identifying the Products of Chemical Reactions

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Easy
Medium
1a5 marks

Chemical tests are used to identify gases, anions and cations.

Draw lines to match the gas to the correct chemical test.

q16a-paper-2-specimen-2016-ocr-gcse-chem

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1b3 marks

A student uses the flame test to identify the cations in a solid.

Describe how she should do a flame test.

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1c1 mark

The student does three chemical tests on an unknown solution.

Look at her results.

Chemical test Result
pH probe pH value is 3
dilute hydrochloric acid followed by barium chloride solution white precipitate
dilute nitric acid followed by silver nitrate solution white precipitate

Which ions are present in the solution?

Choose from:

calcium              hydrogen            iron(II) chloride          sulfate

Explain your answer.

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1a1 mark

A student investigates a white solid.

Table 17.1 shows some of the results of the tests that the student does.

  Test Results
Test 1 flame test a lilac flame
Test 2 dilute hydrochloric acid added
gas given off passed into limewater		 effervescence
?

Table 17.1

Which ion is shown to be in the white solid by the result of Test 1?

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1b2 marks
i)
Which ion is shown to be in the white solid by the result of Test 2?

[1]

ii)
The gas given off in Test 2 is carbon dioxide, CO2.

What is the expected result with limewater?

[1]

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1c4 marks

The student reacts some metals with different salt solutions.

Table 17.2 shows her results.

  Magnesium Zinc Iron Copper
Copper sulfate blue solution
becomes
colourless		 blue solution
becomes
colourless		 blue solution
becomes
green		 no reaction
Iron sulfate green solution
becomes
colourless		 green solution
becomes
colourless		 no reaction no reaction
Magnesium sulfate no reaction no reaction no reaction no reaction
Zinc sulfate black coating
on magnesium		 no reaction no reaction no reaction

Table 17.2

i)
What colour is iron sulfate solution?

[1]

ii)
Write down the order of reactivity of the four metals copper, iron, magnesium and zinc.

Use Table 17.2 to help you.

........................................... most reactive
...........................................
...........................................
........................................... least reactive 

[2]

iii)
Magnesium reacts with copper sulfate, CuSO4.

Magnesium sulfate, MgSO4, and copper are made.

Write the balanced symbol equation for this reaction.

[1]

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2a3 marks

A student wants to identify the ions contained in a solid, X.

She dissolves the solid in some water and then does some tests on the solution.

Look at the table of her results.

Test Method Observations
Test 1 Flame test Red flame seen
Test 2 Add dilute sodium hydroxide solution White precipitate forms which re-dissolves in excess sodium hydroxide solution
Test 3

Add dilute nitric acid, then silver nitrate solution

 White precipitate forms
Test 4

Add dilute hydrochloric acid, then barium chloride solution

 No change – mixture stays clear and colourless

Describe how the student does the flame test in Test 1.

You may draw a labelled diagram to help your answer.

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2b6 marks

The student thinks that solid X contains only lithium ions, Li+, and sulfate ions, SO42-.

Use her results to explain if she is correct.

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