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

 Identifying the Products of Chemical Reactions (OCR Gateway GCSE Chemistry)

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4.2 Identifying the Products of Chemical Reactions

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4.2 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.

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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

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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

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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

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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

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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

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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

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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-

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71 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

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81 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

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    91 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

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    101 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

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      111 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

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      121 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

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      131 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)

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      141 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

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      151 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.

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      161 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

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      171 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

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      181 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.

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      191 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.

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      201 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.

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      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

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