Qualitative Analysis

A metal carbonate reacts with an acid to form…(3)

salt

carbon dioxide

water

Complete this ionic equation:
CO3^2-(aq)+2H+(aq)→....

CO₂(g)+H₂O(l)

We can test for SO4^2-​ ions using…

BaCl₂ and a white precipitate should form

Complete this balanced equation:
BaCl2(aq)+Na2SO4(aq)→…

2NaCl(aq)+BaSO₄(s)

We can confirm our solution contains bubbles of carbon dioxide using…

• limewater

We can test for halide ions using…

AgNO₃

To distinguish between silver halide precipitates, we may need to add…

dilute NH3

concentrated NH3

Which of the following precipitates dissolves in dilute NH3?

AgCl

Which of the following precipitates dissolves in concentrated NH3?

AgBr

Which of these anions can silver nitrate react with?

CO₃^2- and SO₄^2-

Order the following reagents in the sequence we should add them to our unknown solution:(4)

1)acid

2)BaCl₂

3)AgNO₃

4)NH₃

If ammonium cations are present, the litmus paper will...

turn blue.

Which of the following could we use to test for ammonium cations? (2)

NaOH/Ca(OH)₂

_{and red litmus paper would change to blue}

Complete this equation:
NH₄⁺(aq)+OH^-(aq)→

NH₃(g)+H₂O(l)

Few students want to confirm they have a solution of ammonium carbonate. Describe 2 tests they can use to identify the ions that should be present in the solution and include any observations in your answer.

The students can test whether their sample contains carbonate ions by adding an acid. If the sample contains carbonate ions, the reaction will produce bubbles. The bubbles can then be run through limewater. If the limewater turns cloudy - this confirms that these gas bubbles are carbon dioxide.

In addition, the students can test for ammonium cations using a hydroxide, like sodium hydroxide. The students should heat the solution and the hydroxide together, and then place a piece of damp red litmus paper near the mouth of the container. If the litmus paper turns blue, this confirms that ammonium cations are present.

Few students want to confirm they have a solution of ammonium carbonate.

1)Write the ionic equation for the reaction that occurs if the anion is present.

2)Write the ionic equation for the reaction that occurs if the cation is present.

1)2H⁺+CO₃^2-—>H₂O+CO₂

2)NH₄⁺+OH^- —>NH₃+H₂O