N5 Chemistry Chemical Analysis MC 2015-2019 & 2022-2023

Which of the following diagrams shows the apparatus which would allow a soluble gas to be

removed from a mixture of gases?

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Answer explanation

A Gas would not need to pass through water to escape

B Gas would not pass through water (test tube would explode as pressure builds)

C Gas passes through water and escapes test tube through tube at top

D Gas would pass through water but test tube would explode as pressure builds

Which of the following solutions would produce a precipitate when mixed together?

You may wish to use the data booklet to help you.

• Ammonium chloride and potassium nitrate

• Zinc nitrate and magnesium sulfate

• Calcium nitrate and nickel chloride

• Sodium iodide and silver nitrate

Answer explanation

A swap names: ammonium nitrate and potassium chloride are both very soluble

B swap names: zinc sulphate and magnesium nitrate are both very soluble

C swap names: calcium chloride and nickel chloride are both very soluble

D swap names: sodium nitrate is very soluble but silver iodide is insoluble

The lowest temperature at which a hydrocarbon ignites is called its flash point. Using information in the table, identify the correct statement.

• Octane will ignite at 0 ºC.

• Hydrocarbons with the same molecular mass have the same flash point.

• The flash point of a hydrocarbon increases as the boiling point increases.

• In a homologous series the flash point decreases as the number of carbon atoms

  increases.

A solution of potassium carbonate, made up using tap water, was found to be cloudy.

This could result from the tap water containing

You may wish to use the data booklet to help you.

• lithium ions

• calcium ions

• sodium ions

• ammonium ions

Answer explanation

Calcium carbonate is insoluble in water

Which of the following salts can be prepared by a precipitation reaction?

You may wish to use the data booklet to help you.

• Barium sulfate

• Lithium nitrate

• Calcium chloride

• Ammonium phosphate

Answer explanation

Barium sulphate is an insoluble salt and can be made by a precipitation reaction.

The other salts are all soluble.

A solution of accurately known concentration is more commonly known as a

• correct solution

• precise solution

• standard solution

• prepared solution

Answer explanation

A standard solution is a solution whose concentration is accurately known and used in titration to work out the number of moles or concentration of a second substance.

A student set up an experiment to determine the quantity of energy released when a

hydrocarbon burns.

Which of the following diagrams shows the apparatus which would produce the most

accurate result?

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Answer explanation

A draught shield and metal can should be used.

2K⁺(aq) + 2I^–(aq) + Pb²⁺(aq) + 2NO₃ − (aq) --> PbI₂(s) + 2K⁺(aq) + 2NO₃⁻(aq)

The type of reaction represented by this equation is

• neutralisation

• precipitation

• addition

• redox

Answer explanation

neutralisation: reaction of H+ ions to form H2O

precipitation: two ions combining to form an insoluble solid.

addition: adding a molecule across a C=C double bond

redox: electrons are transferred between reduction and oxidation reactions

A student prepared a sample of copper sulfate crystals by reacting excess copper carbonate

with acid. Which line in the table shows the correct order in which this experiment would be carried

out?

• Y, X, Z

• X, Y, Z

• Z, Y, X

• Y, Z, X

Limewater can be made by dissolving calcium hydroxide in water.

Which of the following terms correctly describes calcium hydroxide?

• Solute

• Solvent

• Solution

• Insoluble

Answer explanation

The solute is calcium hydroxide which is dissolved in the solvent (water) to make a solution of limewater.