Identification of Ions & Gases (Cambridge O Level Chemistry)

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

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.

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.

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 ______________________

Copper reacts with concentrated nitric acid to form copper(II) nitrate.

Cu (s) + 4HNO₃ (aq) → Cu(NO₃)₂ (aq) + 2NO₂ (g) + 2H₂O (l)

State the meaning of (aq).

An excess of copper is added to 25.0 cm³ of 16.0 mol / dm³ HNO₃.

Use this information, together with the equation, to calculate the volume of NO₂ formed. The gas volume is measured at room temperature and pressure.

Show your working and state the units.

When heated, Cu(NO₃)₂ decomposes to form CuO, NO₂ and O₂.

Construct the symbol equation for this reaction.

To a small sample of Cu(NO₃)₂ (aq), a student adds aqueous ammonia drop by drop until it is in excess.

[2]

[1]

This question is about ammonium compounds.

An investigation into how the rate of reaction is affected by temperature is completed using the apparatus shown.

The time taken for the magnesium to stop reacting is measured.

Solutions A, B and C were analysed.

Tests were done on each substance.

[3]

A student investigates the mass of dissolved salts in 50 cm³ of an unknown solution. The solution is thought to contain sodium chloride and sodium carbonate.

The tests and some of the observations from the student's investigation are in the following table.

A mixture of two solid compounds D and E was analysed. Solid D was a zinc salt which is soluble in water. Solid E was an insoluble metal carbonate. The tests on the mixture and some of the observations are in the following table.

Test 1: About half of the mixture of D and E was placed in a test-tube. The mixture was heated.

Observations:  Green to black, condensation formed

The rest of the mixture of D and E was added to distilled water in a boiling tube. The contents of the tube were filtered. The filtrate and the residue were kept for the following tests.