Methods of Identifying Ions Practice Questions

Complete the table to give the missing flame colours.

A solution of a single ionic compound produced a green flame in a flame test.

Name the metal ion in this compound.

Name the two solutions the student should add to test for bromide ions in the solution.

Give the result of a positive test for bromide ions.

The student tested a different solution in the same way. A white precipitate formed.

Name the halide ion present in this solution.

A technician thinks that a white solid is zinc carbonate.

Describe a test the technician could do to show that the solid contains carbonate ions.

Give the result of a positive test.

Name the instrumental method used to analyse metal ions in solutions.

Give two advantages of using instrumental methods instead of the chemical tests carried out in a school laboratory.

Complete the table to give the colour of the precipitate formed when a few drops of sodium hydroxide solution are added to each solution.

Magnesium nitrate solution and aluminium nitrate solution both form a white precipitate when a few drops of sodium hydroxide solution are added.

Describe how the student could use sodium hydroxide solution to tell the two solutions apart.

Sodium hydroxide solution is added to magnesium sulfate solution. A white precipitate of magnesium hydroxide forms and sodium sulfate solution is produced.

Write a balanced symbol equation for this reaction.

Include state symbols.

Write the balanced ionic equation, including state symbols, for the formation of the precipitate when sodium hydroxide solution is added to a solution containing iron(II) ions.

Describe how the student should carry out a flame test on the mixture.

The flame test on the mixture produced only a yellow flame.

Explain why the student did not see a crimson flame colour.

Name an instrumental method that could show that both metal ions are present in the mixture.

Describe the test for sulfate ions in solution and give the result of a positive test.

Before carrying out the test, a few drops of dilute hydrochloric acid are added to the solution.

Explain why.

Explain why dilute sulfuric acid must not be used instead of dilute hydrochloric acid in this test.

Identify the metal ion in solution Q.

Give a reason for your answer.

Identify the negative ion in solution Q.

Give a reason for your answer.

Give the formula of the compound in solution Q.

Describe how a line spectrum is produced from a solution in flame emission spectroscopy.

Use the table and the line spectrum to identify the metal ions in solution Y.

Give a reason for each answer.

Give one reason why flame emission spectroscopy is more useful than a flame test for analysing solution Y.

Describe how the technician could use chemical tests to identify which solid is in each bottle.

In your answer you should give the results that would allow each solid to be identified.

Write a balanced symbol equation, including state symbols, for the reaction of aluminium chloride solution with sodium hydroxide solution to form a precipitate of aluminium hydroxide.

A sample of river water gave a line at 589 nm with an intensity of 60 arbitrary units.

Calculate the concentration of sodium ions in this sample of river water.

Give your answer in mg/dm$^3$.

A second sample of river water was found to contain sodium ions, potassium ions and calcium ions.

Explain why flame tests would not have shown that all three of these metal ions were present in this sample.

Explain why the water company uses flame emission spectroscopy rather than chemical tests to monitor the metal ions in river water.