Identification of Ions & Gases (Cambridge (CIE) IGCSE Chemistry)

Extended Only

Choose a gas from the following list to answer the questions below.

Each gas may be used once, more than once or not at all.

It polymerises to form a poly(alkene).

It is a noble gas.

It is the main component of air.

It is a very reactive non-metal.

It burns to form water as the only product.

Choose a gas from the following list to answer the questions below. Each gas may be used once, more than once or not at all.

ammonia    argon    chlorine   ethene    hydrogen   

carbon dioxide   nitrogen   carbon monoxide   oxygen

Which gas

i) Is a noble gas?

[1]

ii) Is an acidic oxide?

[1]

iii) Can be polymerised?

[1]

iv) Is the active component of air?

[1]

v) Is used in the treatment of water?

[1]

Complete the following table.

Table 1 shows the mass of ions present in a 100 cm³ sample of milk.                                                                          

Table 1

Describe a test for chloride ions.

 test ..................................................

 positive result  ..................................................

Calcium reacts with cold water to form two products:

• a colourless gas, P, which ‘pops’ with a lighted splint

• a weakly alkaline solution, Q, which turns milky when carbon dioxide is bubbled through it.

i) Name gas P.

 [1]

 ii) Name the weakly alkaline solution Q.

 [1]

This question is about ammonia and ammonium salts.

Ammonia is a gas at room temperature. What is the test for ammonia gas? Describe the positive result of this test.

test .......................................................................

result ....................................................................

Ammonia reacts with water to form ions.                                            

NH₃ + H₂O NH₄⁺ + OH^–

Describe what is seen when aqueous ammonia is added to aqueous copper(II) sulfate, until no further change is seen.

Barium sulfate is an insoluble salt.

Barium sulfate can be made from aqueous ammonium sulfate using a precipitation reaction.

Name a solution that can be added to aqueous ammonium sulfate to produce a precipitate of barium sulfate.

This question is about tests for ions.

Describe the test for a nitrate ion.

test ___________________________

result __________________________

Describe a test for iodide ions.

test ______________________________

observations ______________________

This question is about ammonium compounds.

The table shows the names and formulae of some ammonium compounds.

 i) Complete the table by giving the missing information.

[2]

 ii) When ammonia reacts with nitric acid, ammonium nitrate is formed.

Write a chemical equation for this reaction.

 [1]

Extended Only

When ammonium chloride is heated, it undergoes thermal decomposition to form two gaseous products.

 Describe the result of testing each product with damp universal indicator paper.

Extended Only

The diagram shows the apparatus used to heat ammonium chloride.

i) Suggest why the damp litmus paper is two different colours.

 [1]

 ii) Explain what happens to the damp litmus paper as the ammonium chloride is heated. 

 [3]

Extended Only

Explain why a fine white powder formed on the inside of the neck of the conical flask in part (c).