OCR A Level Chemistry

Topic Questions

A LevelChemistryOCRTopic Questions1. Development of Practical Skills in Chemistry1.2 Organic & Inorganic Practicals

1.2 Organic & Inorganic Practicals

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11 mark

A student adds a few drops of dilute nitric acid followed by a few drops of silver nitrate solution to a test tube containing an unknown colourless solution. A white precipitate is seen.

What ions could be present in the colourless solution?

  • Ammonium ions

  • Chloride ions

  • Sulfate ions

  • Magnesium ions

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21 mark

An ammonium sulfate solution is warmed in a test tube with a few drops of sodium hydroxide solution. A piece of damp red litmus paper is held near the mouth of the test tube.

Which of the following statements is true?

  • The litmus paper will turn blue

  • The litmus paper will remain red

  • The gas given off is sulfur dioxide

  • The gas given off is colourless and odourless

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31 mark

An aqueous cation from Group 2 is first tested with sodium hydroxide solution and then with dilute sulfuric acid. 

Test

Result

Addition of sodium hydroxide

No reaction

Addition of sulfuric acid

White precipitate

Which cation could be present?

  • Magnesium

  • Barium

  • Calcium

  • Strontium

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41 mark

Which of these anions produces a yellow precipitate when treated with acidified silver nitrate solution?

  • F–

  • Cl–

  • Br

  • I–

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51 mark

Some standard laboratory equipment is shown below

7th

What reaction could this apparatus be used for?

  • Preparing a carboxylic acid

  • Cracking an alkane

  • Oxidising an alcohol

  • Halogenation of an alkene

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61 mark

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Some standard laboratory equipment is shown below, but the labels are missing.

The purpose of the part labelled X is 

  • To check the boiling point of the reaction mixture

  • To separate the distillate from the reaction mixture

  • To check the purity of the distillate

  • To prevent gases from escaping

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71 mark

The preparation of organic liquids, such as some alcohols, can involve heating under reflux.

Which statement about heating under reflux is correct?

  • You can heat organic liquids without evaporation taking place

  • You can maintain organic liquids at their boiling point for extended periods

  • Heating is carried out indirectly using a water bath

  • The apparatus is closed to prevent the escape of materials

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81 mark

Which of the following can be done with the aid of a separating funnel?

 

Neutralise acidic impurities

Dry organic liquids

Separate miscible liquids

A

✔

✔

✔

B

✔

✔

x

C

x

✔

✔

D

✔

x

x

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91 mark

A mixture of hex-1-ene and hexan-2-ol undergoes a series of chemical tests.

Which of the following shows the correct results for hex-1-ene and hexan-2-ol?

  Test Result for hex-1-ene Result for hexan-2-ol
A Shake with bromine water Colourless to orange  No change
B Shake with acidified KMnO4 No change Purple to colourless 
C Addition of sodium metal No reaction  Fizzing seen
D Combustion  Smokey flame  Very smokey flame

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101 mark

A number of experimental steps are followed during the preparation and purification of cyclohexene.

Which of the following does not have the correct pair of experimental steps and reason for the step?

  Experimental step Reason
A Add a few anti-bumping granules to the distillation flask  To trap impurities
B Heat the flask gently using an electric heater Cyclohexanol is flammable
C Shake the separating funnel and open the stopcock periodically To release pressure
D Add solid anhydrous calcium chloride to the crude cyclohexene To remove water

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11 mark

Chemical tests can be used to determine the presence of aqueous ions. The following tests were carried out on the product of the reaction between ammonia and sulfuric acid.

Test 1: 10 drops of sodium hydroxide followed by a water bath

Test 2: Dilute hydrochloric acid followed by a few drops of aqueous barium chloride

Which row is correct?

 

Test 1 result

Test 2 result

A

Damp red litmus paper turns blue

Colourless solution

B

Damp red litmus paper turns blue

White precipitate

C

Damp blue litmus paper turns red

Colourless solution

D

Damp blue litmus paper turns red

White precipitate

 

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21 mark

Haloalkanes can be synthesised from alcohols and hydrogen halides (HX) using a separating funnel.

Which of the following statements is/are correct?

  1. Anhydrous magnesium sulfate is added to the organic layer following separation to remove water.
  2. Following the substitution reaction, sodium hydrogen carbonate is added to remove any alkaline impurities.
  3. In the separating funnel, the organic layer will be higher because it is more dense than the aqueous layer.

  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1

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31 mark

Cyclohexene can be prepared from cyclohexanol by distillation with a concentrated phosphoric acid catalyst followed by purification using a separating funnel.

Which of the following statements is/are incorrect in this experiment?

  1. Anti-bumping granules are used to reach the boiling point more quickly so that the product will not be contaminated.
  2. The distillate can be tested for the presence of cyclohexene by using lime water which will produce a cloudy solution.
  3. In the elimination reaction, water is released from the -OH group and an adjacent hydrogen atom.

  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1

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41 mark

Acidified potassium dichromate(VI) can be used to form ethanal and ethanoic acid from ethanol.

Which row of the statements below is correct?

 

Role of acidified potassium dichromate(VI)

Change in oxidation number

Colour change

A

Oxidising agent

Cr3+ → Cr6+

Green to orange

B

Reducing agent

Cr6+ → Cr3+

Green to orange

C

Reducing agent

Cr3+ → Cr6+

Orange to green

D

Oxidising agent

Cr6+ → Cr3+

Orange to green

 

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51 mark

Hex-1-ene can be hydrated to form an alcohol. The product is separated, distilled and tested.

Which statement is correct for this experiment?

  • Hexan-2-ol has a lower boiling point than hex-1-ene due to the presence of hydrogen bonds.

  • Hexan-2-ol has a higher boiling point than hex-1-ene due to having temporary induced dipole-dipole forces between molecules.

  • Hexan-2-ol is the major product because the secondary carbocation intermediate is more stable.

  • The sulfuric acid catalyst is reformed following homolytic cleavage of the -OH bond within the water molecule.

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11 mark

Which of these anions forms a white precipitate when tested with acidified silver nitrate solution?

  • CO32-

  • SO42-

  • OH-

  • Cl-

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21 mark

A halogenoalkane is heated with aqueous sodium hydroxide and ethanol. The solution is then acidified with dilute nitric acid and silver nitrate solution is added. A cream coloured precipitate is seen.

Which halogenoalkane could be present?

  • CH3F

  • CH3Cl

  • CH3Br

  • CH3I

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31 mark

What happens when a piece of strontium is placed in cold water?

  • Bubbles of gas form slowly on the strontium

  • A vigorous effervescence occurs

  • The strontium floats on the surface of the water and reacts quickly

  • The strontium burns with a bright white flame and a white solid is produced

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41 mark

Which reagent could detect the presence of butan-1-ol ?

  • Tollens’ reagent

  • Br2 (aq)

  • K2CrO7 (aq)

  • Fehling’s reagent

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51 mark

Which statement is correct about recrystallisation in the preparation of an organic solid?

  • The organic solid must be insoluble in the hot solvent

  • The impurities remain dissolved in the solvent after cooling

  • The yield of the product is increased

  • The melting point of the solid is lowered after recrystallisation

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61 mark

A student prepared a sample of a haloalkane from an alcohol. She added sodium hydrogen carbonate to the separating funnel.  What is the reason for adding sodium hydrogen carbonate? 

  • To remove the water

  • To remove impurites

  • To neutralise unreacted acid

  • To improve solubility of the alcohol 

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71 mark

Cyclohexene can be prepared in the laboratory by distilling cyclohexanol with concentrated phosphoric acid.

The boiling points of water, cyclohexanol and cyclohexene are 100 °C, 162 °C and  83 °C respectively.

Which of the following statements is correct?

  • The concentrated phosphoric acid acts as an oxidising agent

  • Cyclohexanol is soluble in water

  • A separating funnel is needed to isolate the product

  • The distillate only contains organic liquids

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81 mark

What happens when iodine is bubbled through aqueous potassium bromide?

  • Iodine is oxidised to iodide ions

  • Potassium bromide is reduced to bromine

  • No reaction occurs

  • Bromide ions are oxidised to bromine

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91 mark

Which of the following reagents can be used to dry a sample of cyclohexene?

  • Anhydrous calcium chloride 

  • Saturated sodium carbonate solution

  • Aluminium oxide 

  • Porcelain chips 

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101 mark

Which of the following pairs of compounds will produce bubbles of gas when mixed together? 

  • BaCl2 and H2SO4

  • Na2CO3 and CH3COOH

  • AgBr and concentrated NH3

  • MgCO3 and excess NaOH 

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