Virtual CrezLab - Qualitative Analysis

A.	All gases must be tested when a substance is heated.
B.	Oxygen gas is produced only when acids react with compounds containing oxygen.
C.	Some compounds decompose on heating to give oxygen gas.
D.	Oxygen gas will not be liberated during heating, instead it react with the unknown solid.

A student believes that she has to test for hydrogen and carbon dioxide when she heats an unknown ionic compound in powder form. Do you agree?

A.	Yes
B.	No

For Question 3, choose the reason/justification.

A.	Ionic compounds have strong bonds and do not decompose on heating.
B.	Most carbonates decompose on heating to give carbon dioxide but hydrogen is never liberated when any ionic compound is heated.
C.	The ionic compound would react with oxygen on heating to give water and/or carbon dioxide.
D.	Those ionic compounds containing carbonate, hydrogen or hydroxide ions will liberate carbon dioxide or hydrogen on heating.

A student is given a solution which may contain a carbonate ion. She decides to add aqueous barium nitrate to the solution first, followed by dilute nitric acid. Is it possible for her to determine whether a carbonate ion is present when she carries out the above procedure?

A.	Yes
B.	No

For Question 5, choose the reason/justification.

A.	Dilute nitric acid will react with both a soluble and an insoluble carbonate.
B.	The above procedure is strictly to test for the presence of sulphate ions only.
C.	The unknown compound will only react with the dilute nitric acid and not with the barium nitrate.
D.	The acid must be added directly to the solution to test for the presence of a carbonate.

Instead of nitric acid, can the student add dilute sulphuric acid, H₂SO₄, after the addition of barium nitrate in Question 5?

A.	Yes
B.	No

For Question 7, choose the reason/justification.

A.	Any acid can be used as they have similar properties and reactions.
B.	Sulphate ions from dilute sulphuric acid will interfere with the test.
C.	The addition of barium nitrate has already invalidated(spoilt) the test for carbonates.
D.	Dilute sulphuric acid will react with the nitrate ions.

Two bottles in a laboratory are unlabelled. One bottle is known to contain aqueous sodium iodide and the other aqueous sodium chloride. A student attempts to identify the solutions by carrying two different tests. Which of the following test would identify the solutions?

A.	Addition of aqueous silver nitrate
B.	Addition of aqueous barium nitrate

10.

For Question 9, choose the reason/justification.

A.	Iodide ions will react with silver ions to form a pale yellow precipitate whereas chloride ions will react with silver ions to form a white precipitate.
B.	Aqueous barium nitrate will also test for the presence of sulphate and carbonate ions.
C.	Only chloride ions will react with silver ions to form a white precipitate, iodide ions do not react with silver nitrate.
D.	Aqueous barium nitrate will react with chloride ions to form a white precipitate.

11.

Aqueous sodium hydroxide reacts with a metal ion producing a coloured precipitate. This precipitate changes colour on standing. What is the ion present?

A.	Fe²⁺
B.	Fe³⁺

12.

For Question 11, choose the reason/justification.

A.	Reddish brown iron(III) oxide which is reduced to dirty green iron(II) oxide on standing.
B.	Dirty green iron(II) hydroxide is oxidised to reddish brown iron(III) hydroxide on standing.
C.	Reddish brown iron(III) hydroxide is decomposed on standing to form dirty green iron(II) oxide.
D.	Dirty green iron(II) hydroxide is reduced to reddish brown iron(III) hydroxide on standing.

13.

An excess of sodium hydroxide is added to an aqueous solution of salt X and boiled. Ammonia gas is only given off after aluminium foil is added to the hot solution. What could be X?

A.	Sodium nitrate
B.	Ammonium nitrate

14.

For Question 13, choose the reason/justification.

A.	Ammonia gas is only liberated by ammonium ions when heated with dilute acids.
B.	Nitrate ions displaced by the more reactive aluminium metal to form ammonia gas.
C.	Ammonia gas is also liberated by ammonium ions when heated with alkalis.
D.	Nitrate ions are oxidised to ammonia gas by heating with the aluminium foil.

15.

A sample of an alloy containing two metals was dissolved in dilute sulphuric acid. Aqueous sodium hydroxide was then added to the mixture. A precipitate was formed. An excess of the alkali caused the mass of the precipitate to decrease leaving a dirty green solid and a colourless solution. What were the two metals present in the alloy?

A.	Zinc and iron
B.	Copper and iron

16.

For Question 15, choose the reason/justification.

A.	Copper reacts with dilute sulphuric acid to form copper(II) ions which forms a blue precipitate with sodium hydroxide.
B.	Zinc ions forms a white precipitate that is insoluble in excess sodium hydroxide.
C.	Zinc reacts with dilute sulphuric acid to form a colourless solution of zinc sulphate.
D.	Zinc ions forms a white precipitate reacts with excess sodium hydroxide to form a complex salt that dissolves to form a colourless solution.

17.

Which of the compounds below when added to aqueous iron(II) sulphate, would give a final mixture that is yellow in colour?

A.	potassium iodide
B.	potassium manganate(VII)

18.

For Question 17, choose the reason/justification.

A.	Potassium manganate(VII) acts as an oxidizing agent that oxidizes pale green iron(II) ions to yellow iron(III) ions.
B.	Potassium iodide(VII) acts as an oxidizing agent that oxidizes pale green iron(II) ions to yellow iron(III) ions.
C.	Potassium manganate(VII) acts as a reducing agent that reduces pale green iron(II) ions to yellow iron(III) ions.
D.	Potassium iodide(VII) acts as a reducing agent that oxidizes pale green iron(II) ions to yellow iron(III) ions.

19.

Dilute nitric acid and dilute hydrochloric acid could best be distinguished by adding

A.	copper(II) carbonate
B.	silver nitrate solution

20.

For Question 19, choose the reason/justification.

A.	Only chloride ions from dilute hydrochloric acid will react with silver nitrate to form a white precipitate of silver chloride.
B.	Copper(II) carbonate will dissolve in nitric acid to form a blue solution.
C.	Only carbonate ions from copper(II) carbonate will react with silver nitrate to form a white precipitate of silver carbonate.
D.	Copper(II) carbonate will dissolve in hydrochloric acid to form a green solution.

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