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GCSEChemistryOCRChemistry A (Gateway)Exam Questions4. Predicting & Identifying Reactions & ProductsIdentifying the Products of Chemical Reactions

Identifying the Products of Chemical Reactions (OCR GCSE Chemistry A (Gateway)): Exam Questions

Exam code: J248

49 mins27 questions

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Identifying the Products of Chemical Reactions

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11 mark

Damp litmus paper is used to test for chlorine gas.

Which statement describes the correct result of the test for chlorine gas?

  • Damp blue litmus paper turns red then white.

  • Damp blue litmus paper turns white then red.

  • Damp red litmus paper turns blue then white.

  • Damp red litmus paper turns white then blue.

Choose your answer

21 mark

A student adds sodium hydroxide solution to a small sample of copper(II) chloride solution.

A precipitate is made.

What is the colour of the precipitate?

  • Blue

  • Green

  • Orange

  • White

Choose your answer

31 mark

The table shows the stages in a flame test.

Stage

Process

1

Dip a nichrome wire loop into the test solution

2

Observe and record the flame colour

3

Clean a nichrome wire loop with hydrochloric acid, then rinse with distilled water

4

Hold the nichrome wire loop in the edge of a roaring blue flame

Which is the correct order for the stages in a flame test?

  • 1, 4, 2, 3

  • 1, 4, 3, 2

  • 3, 1, 4, 2

  • 3, 4, 1, 2

Choose your answer

41 mark

A student does a flame test with a sample of potassium chloride.

Which colour is the flame?

  • Lilac

  • Green-blue

  • Red

  • Yellow

Choose your answer

51 mark

What is the test for chlorine gas?

  • Damp universal indicator paper turns red then white

  • Decolourises bromine water

  • Limewater turns milky

  • Relights a glowing splint

Choose your answer

11 mark

During the electrolysis of brine, chlorine gas forms at one electrode.

2Cl- (aq) rightwards arrowCl2 (g) + 2e-

Which test would be most appropriate to confirm that chlorine gas was produced?

  • Collect the gas and see if it extinguishes a glowing splint

  • Collect the gas and check if it is green

  • Collect the gas and see if it bleaches damp litmus paper

  • Collect the gas and check if it smells of swimming pools

Choose your answer

21 mark

Which is the correct method for testing for hydrogen gas?

  • Hold the tube containing the gas upright and place a lit splint at the end of the tube

  • Hold the tube containing the gas upright and place a glowing splint at the end of the tube

  • Hold the tube containing the gas angled down and place a lit splint at the end of the tube

  • Hold the tube containing the gas angled down and place a glowing splint at the end of the tube

Choose your answer

31 mark

Which is not true about the test for carbon dioxide gas?

  • The gas is bubbled through limewater solution

  • Limewater is calcium hydroxide solution

  • The solution will turn cloudy due to the formation of a white precipitate

  • The colour will fade after a few minutes

Choose your answer

41 mark

What is the correct observation when a glowing splint is held at the entrance of a tube of pure oxygen gas? 

  • A 'squeaky pop' sound can be heard

  • The glowing splint relights

  • The glowing splint keeps glowing

  • The glowing splint is immediately extinguished

Choose your answer

51 mark

The electrolysis of fresh water produces hydrogen gas and oxygen gas.

The electrolysis of salt water (brine) produces hydrogen gas and chlorine, and leaves a solution of sodium hydroxide.

Which test would not help to identify a sample as being fresh water or salt water?

  • A gas collected makes a 'squeaky pop' when a lit splint is held in it

  • A gas collected relights a glowing splint

  • A gas collected bleaches damp litmus paper

  • The pH of the solution increases

Choose your answer

61 mark

Scientists test a solution of compound X.

Table 1 shows their results.

Table 1

Test

Result

Add dilute nitric acid followed by silver nitrate solution

White precipitate

Add sodium hydroxide solution

Green precipitate

Which two ions are present in compound X?

  • Fe3+ and Cl-

  • Fe3+ and SO42-

  • Fe2+ and Cl-

  • Fe2+ and SO42-

Choose your answer

71 mark

A compound is suspected of containing calcium ions, Ca2+.

Which test would not help to positively identify calcium?

 

Test

Result

A

Flame test

Orange-red flame

B

Add sodium hydroxide solution

White precipitate forms

C

Add nitric acid and silver nitrate

White precipitate forms

D

Flame photometry

Characteristic lines match the reference spectrum

    Choose your answer

    81 mark

    Which is not an advantage of using instrumental methods rather than small-scale lab methods for identifying ions?

    • Instrumental methods are more accurate

    • Instrumental methods are faster

    • Instrumental methods are cheaper

    • Instrumental methods are more sensitive

    Choose your answer

    91 mark

    Which element is present in this flame emission spectrum?

    emission-spectrum-of-mercury

    Reference line emission spectra chart

    reference-spectra

    • Helium

    • Mercury

    • Hydrogen

    • Neon

    Choose your answer

    101 mark

    A student adds a few drops of sodium hydroxide solution to an unknown solution and a blue precipitate is made.

    Which metal ion is present in the original solution?

    • Calcium

    • Copper(II)

    • Iron(II)

    • Iron(III)

    Choose your answer

    111 mark

    Which statement describes the test for chlorine gas?

    • A lighted splint makes a squeaky pop.

    • Limewater turns milky.

    • A glowing splint re-lights.

    • Damp litmus paper is bleached.

    Choose your answer

    121 mark

    A student is testing sodium carbonate solution.

    She adds barium chloride solution followed by excess dilute hydrochloric acid.

    Which of these observations would not be seen?

    • Colourless solution at the end

    • Gas bubbles when the dilute acid is added

    • White precipitate formed when the barium chloride solution is added

    • White precipitate formed when the dilute acid is added

    Choose your answer

    131 mark

    Which statement describes the advantages of instrumental methods of analysis?

    • Instruments can analyse very small amounts and carry out the analyses slowly.

    • Instruments are very accurate and use large amounts of substances.

    • Instruments are very accurate and carry out the analyses slowly.

    • Instruments are very accurate and can run all the time.

    Choose your answer

    141 mark

    A student tests a solution for chloride ions.

    She adds dilute nitric acid to the solution. She then adds a few drops of silver nitrate solution.

    Why does she need to add dilute nitric acid in this test?

    • To increase the pH of the solution.

    • Nitrate ions are needed for the test to work.

    • To make sure that no carbonate ions are present.

    • The test only works in alkaline conditions.

    Choose your answer

    11 mark

    Which statement about a mass spectrum of a molecule is correct?

    • Each peak represents an atom in the molecule.

    • The charge to mass ratio of the molecular ion peak is equal to the relative formula mass of the molecule.

    • The peak with the highest relative abundance represents the molecular ion.

    • The peak on the far right of the spectrum represents the molecular ion.

    Choose your answer

    21 mark

    Look at the mass spectrum of a carbon compound.

    a-mass-spectrum

    Which carbon compound is this mass spectrum from?

    • C4H10+

    • C3H5O2+

    • C3H8O

    • C4H8

    Choose your answer

    31 mark

    Look at the mass spectrum of a carbon compound.

    q6-paper-2-june-2018-ocr-gcse-chem

    Which carbon compound is the mass spectrum from?

    • C2H2

    • C2H5+

    • C3H7+

    • C4H10

    Choose your answer

    41 mark

    Scientists test a solution from a bottle that is known to contain a copper (II) compound.

    Table 1 shows their results.

    Table 1

    Test

    Result

    Flame test

    Yellow flame

    Add sodium hydroxide solution

    Blue precipitate formed

    Add dilute nitric acid followed by silver nitrate solution

    Yellow precipitate formed

    Which statement below is true?

    • The flame test was performed incorrectly

    • Bromide ions are present, so the compound is CuBr2

    • The test tube was contaminated for the sodium hydroxide test

    • The copper compound in the bottle was contaminated with another metal compound

    Choose your answer

    51 mark

    Calcium carbonate can react with hydrochloric acid by the following equation:

    CaCO3 (s) + HCl (aq) rightwards arrowCaCl2 (aq) + H2O (l) + CO2 (g)

    Which observation does not tell you that this reaction has occurred?

     

    Test

    Result

    A

    Add dilute nitric acid then by silver nitrate solution

    White precipitate forms

    B

    Bubble any gases present through limewater

    Limewater turns cloudy

    C

    Observe the solutions when they are mixed

    Solutions bubble and fizz upon mixing

    D

    Test pH of the solution at the start and after 30 s

    pH increases

      Choose your answer

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