This question is about the identification of ions in unknown solutions.

A student completes a number of test-tube reactions on solutions A, B and C.

The table below shows the student's observations.

Suggest the identity of the positive ion in solution A.

Give the simplest ionic equation for the formation of the white precipitate in Test 1 for solution A.

Different gases are formed when solution B reacts in Test 1 and in Test 2.

Suggest the identity of each gas.

Give the simplest ionic equation for the formation of the gas in Test 2.

The student thinks that solution C contains either chloride ions or bromide ions.

Describe a further test to show whether solution C contains chloride or bromide ions.

Separate unlabelled solid samples of three anhydrous sodium compounds are provided for a student to identify.

These compounds are known to be sodium carbonate, sodium chloride and sodium fluoride but it is not known which sample is which.

Outline a logical sequence of test-tube reactions that the student could carry out to identify each of these compounds.

Include the observations the student would expect to make.

Give equations for any reactions that would take place.

A student carries out test-tube experiments to prove the trend in reactivity of halogens.

The student is provided with the following solutions:

• bromine water
• aqueous iodine
• aqueous barium chloride
• aqueous magnesium bromide
• aqueous calcium iodide.

Chlorine gas and chlorine water are not available.

The student carries out the minimum number of test-tube experiments using these aqueous solutions.

• State the solutions that need to be added together in order to prove the trend in reactivity of the halogens, using the minimum number of test-tube experiments.
• Describe the colour seen at the end of each test-tube experiment.
• Write an ionic equation for one reaction that takes place.

You are supplied with a sample of ammonium bromide.

Describe simple tests that would identify the cation and anion present in ammonium bromide.

Include reagents, expected observations and relevant equations.

The presence of the carbonate ion is usually confirmed using a simple test carried out in two stages at room temperature. Describe this test and its results.

Using barium carbonate as your example, write the equation for each of the stages of the carbonate test. Include state symbols in both equations.

Give a reagent that, when added separately to aqueous magnesium chloride and aqueous barium chloride, could be used to distinguish between them. 

State what is observed in each case.

This question is about ion testing.

Give the reagent and the observation to show the presence of carbonate ions.

Give the reagent and the observation to show the presence of sulfate ions.

Give the reagent and the observation to show the presence of iodide ions.

A student investigated the chemistry of the halogens and the halide ions.

In the first two tests, the student made the following observations.

Identify the species responsible for the brown colour in Test 1.

Write an ionic equation for the reaction that has taken place in Test 1.

State the type of reaction that has taken place in Test 1.

Name the species responsible for the white precipitate in Test 2.

Write an ionic equation for the reaction that has taken place in Test 2.

State what would be observed when an excess of dilute ammonia solution is added to the white precipitate obtained in Test 2.

In two further tests, the student made the following observations.

Write the simplest ionic equation for the reaction that has taken place in Test 3.

Identify the species responsible for the misty white fumes produced in Test 3.

The student had read in a textbook that the equation for one of the reactions in Test 4 is as follows.

8H⁺ + 8I^- + H₂SO₄ ➔ 4I₂ + H₂S + 4H₂O

Write the two half-equations for this reaction.

State the role of the sulfuric acid and identify the yellow solid that is also observed in Test 4.