Qualitative analysis 1

​Qualitative analysis of cations + flame tests + test for gases

Flame tests

Multiple Select

You cannot see positive ions when they are dissolved in a solution. Which 2 chemicals can be used to test for their presence?

• NaOH solution

• NH₃ solution

• H₂SO₄ solution

• HCl solution

Multiple Select

How are the positive ions that are dissolved in a solution identified using these 2 chemicals?

• Observe if precipitate forms

• Add excess of the test solutions and observe if the precipitate dissolves

• Observe if there is a pop sound

• Observe if there are any effervescence

Multiple Select

When tested with aqueous NaOH, these positive ions produce white precipitate. These ions could be

• Cu²⁺

• NH₄⁺

• Al³⁺

• Zn²⁺

• Ca²⁺

Multiple Choice

There are 3 solutions: A,B and C.

When tested with few drops of NaOH solution, 3 of them produce white precipitate. When excess of NaOH solution was added, the precipitate in A and B dissolves to form a clear colourless solution. The precipitate in C did not dissolve. Ion in C is

• NH₄⁺

• Al³⁺

• Zn²⁺

• Ca²⁺

Multiple Choice

When tested with aqueous NH₃, a blue precipitate forms. When excess NH3 is used, the precipitate dissolves to give dark blue solution. This ion is

• Cu²⁺

• NH₄⁺

• Al³⁺

Multiple Select

2 cations will produce green precipitate when tested with few drops of NaOH solution. They are

• Cu²⁺

• Fe²⁺

• Al³⁺

• Cr³⁺

Multiple Select

Since both Fe2+ and Cr3+ ions produce white precipitate when tested with few drops of NaOH, what should you do in order to tell them apart?

• Use NaOH in excess. Fe²⁺ precipitate will dissolve, to produce clear solution.

• Use NaOH in excess. Cr³⁺ precipitate will dissolve, to produce clear solution.

Multiple Choice

Which cation produces white precipitate with few drops of NaOH, but yields no precipitate when tested with NH₃?

• Ca²⁺

• Fe²⁺

• Al³⁺

Multiple Choice

To test for the presence of NH₄⁺ ion, add few drops of NaOH and warm the solution. A gas will be produced. What is the gas produced?

• NH₃ (ammonia)

• H₂ (hydrogen)

• CO₂ (carbon dioxide)

Multiple Choice

Test with lighted splint. There will be a 'pop'

• H₂

• CO₂

• NH₃

• O₂

• Cl₂

Multiple Choice

Test with a glowing split. This gas relights a glowing splint.

• H₂

• CO₂

• NH₃

• O₂

• Cl₂

Multiple Choice

Bubble the gas into limewater. Limewater turns milky.

• H₂

• CO₂

• NH₃

• O₂

• Cl₂

Multiple Choice

Test the gas with a damp red litmus paper. This gas turns red litmus paper blue.

• H₂

• CO₂

• NH₃

• O₂

• Cl₂

Multiple Choice

Test the gas with acidified aqueous potassium manganate (VII) . It turns acidified aqueous potassium manganate(VII) from purple to colourless

• H₂

• CO₂

• NH₃

• O₂

• SO₂