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(GCSE) Chemistry > ✅ 7. Required Practical: Identifying Ions (C12) > Flashcards

✅ 7. Required Practical: Identifying Ions (C12) Flashcards

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1
Q

Aim of this Practical

A

You are going to identify some ionic compounds by testing to identify both the positive and negative ions.

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2
Q

Health and Safety Measures

A

(-Symbols Associate show there are:

  • Oxidising Agents
  • Caution/Harmful
  • Corrosive Substances
  • Wear Safety Goggles)
  • Treat all the compounds as corrosive, harmful, irritant and oxidising.
  • Ensure you stopper the test tube when shaking to dissolve and keep your thumb on the bung.
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3
Q

How do you carry out flame tests for positive ions

A

Place a damp splint into some of the ionic compound as a solid. Then place the splint in a roaring Bunsen flame and look for any colour.

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4
Q

How do you carry out the sodium hydroxide test for positive ions

A

Dissolve a small amount of the solid ionic compound in deionised water (about 3 cm depth). Then add sodium hydroxide solution. If a white precipitate forms, test it further by adding more sodium hydroxide solution.

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5
Q

How do you carry out halide ion tests for negative ions

A

Dissolve a small amount of the solid ionic compound in deionised water (about 3 cm depth). Then add a few drops of nitric acid followed by 1 cm depth of silver nitrate solution.

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6
Q

How do you carry out the sulphate ion test for negative ions

A

Dissolve a small amount of the solid ionic compound in deionised water (about 3 cm depth). Then add a few drops of hydrochloric acid followed by 1cm depth of barium chloride solution.

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7
Q

How do you carry out the carbonate ion test for negative ions

A

Place some hydrochloric acid in a test tube and add a small spatula load of the solid ionic compound. Look for bubbles of gas. If a gas is released then insert a delivery tube into the test tube and bubble the gas through limewater.

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8
Q

What result and test can show positive for Lithium, Li^+ ions

A

A crimson (red) flame from the flame test

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9
Q

What result and test can show positive for Sodium, Na^+ ions

A

A yellow flame from the flame test

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10
Q

What result and test can show positive for Potassium, K^+ ions

A

A lilac (purple) flame from the flame test

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11
Q

What result and test can show positive for Copper, Cu^2+ ions

(+Ionic Equation for the reaction)

A

A green flame from the flame test

OR

Blue precipitate from adding sodium hydroxide (aq)
Cu^2+ (aq) + 2OH^- (aq) —> Cu(OH)2 (s)

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12
Q

What result and test can show positive for Calcium, Ca^2+ ions

(+Ionic Equation for the reaction)

A

An orange-red flame from the flame test

OR

White precipitate (does not dissolve when more NaOH added) from adding Sodium Hydroxide

Ca^2+ (aq) + 2OH^- (aq) —> Ca(OH)2 (s)

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13
Q

What result and test can show positive for Magnesium, Mg^2+ ions

(+Ionic Equation for the reaction)

A

White precipitate (does not dissolve when more NaOH added) from adding Sodium Hydroxide

Mg2+ (aq) + 2OH– (aq) → Mg(OH)2 (s)

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14
Q

What result and test can show positive for Aluminium, Al^3+ ions

(+Ionic Equation for the reaction)

A

White precipitate (dissolves when more NaOH added) from adding Sodium Hydroxide

Al3+ (aq) + 3OH– (aq) → Al(OH)3 (s)

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15
Q

What result and test can show positive for Iron (II), Fe^2+ ions

(+Ionic Equation for the reaction)

A

Green precipitate is formed from adding Sodium Hydroxide

Fe2+ (aq) + 2OH– (aq) → Fe(OH)2 (s)

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16
Q

What result and test can show positive for Iron (III), Fe^3+ ions

(+Ionic Equation for the reaction)

A

Brown precipitate is formed from adding Sodium Hydroxide

Fe3+ (aq) + 3OH– (aq) → Fe(OH)3 (s)

17
Q

What results and tests can show positive for Carbonate, CO3^2- ions

A

Bubbles of gas (that turn limewater cloudy) after adding dilute acid

(would form bubbles of gas when acid added) when barium chloride (aq) with hydrochloric acid are added

(would form bubbles of gas when acid added) when silver nitrate (aq) with nitric acid are added

18
Q

What result and test can show positive for Sulphate, SO4^2- ions

(+Ionic Equation for the reaction)

A

White precipitate is formed after barium chloride (aq) with hydrochloric acid is added

Ba2+ (aq) + SO42– (aq) → BaSO4 (s)

19
Q

What result and test can show positive for Chloride, Cl- ions

(+Ionic Equation for the reaction)

A

White precipitate is formed after silver nitrate (aq) with nitric acid is added

Ag+ (aq) + Cl– (aq) → AgCl (s)

20
Q

What result and test can show positive for Bromide, Br- ions

+Ionic Equation for the reaction

A

Cream precipitate is formed after silver nitrate (aq) with nitric acid is added

Ag+ (aq) + Br– (aq) → AgBr (s)

21
Q

What result and test can show positive for Iodide, I- ions

+Ionic Equation for the reaction

A

Yellow precipitate is formed after silver nitrate (aq) with nitric acid is added

Ag+ (aq) + I– (aq) → AgI (s)

22
Q

Plan a sequence of chemical tests that would distinguish these four compounds. Describe the results that you would expect.

  • Sodium Sulfate
  • Sodium Carbonate
  • Sodium Iodide
  • Potassium Iodide
A

Test 1:
Place a damp splint into some of the ionic compound as a solid. Then place the splint in a roaring Bunsen flame and look for a colour. If sodium is present, it will burn a yellow flame, and is potassium is present, then there will be a lilac flame.

If there is a lilac flame, then that compound is the potassium iodide.

Test 2:
Dissolve a small amount of the solid ionic compound in deionised water (about 3 cm depth). Then add a few drops of nitric acid followed by 1 cm depth of silver nitrate solution. A chloride will give a white precipitate, a bromide will give a cream precipitate, and an iodide will give a yellow precipitate.

If there is a yellow precipitate, then the compound is sodium iodide.

Test 3:
Dissolve a small amount of the solid ionic compound in deionised water (about 3 cm depth). Then add a few drops of hydrochloric acid followed by 1cm depth of barium chloride solution. If sulphate ions are present, a white precipitate will form.

If there is a white precipitate, then the compound is sodium sulphate.

Test 4:
Place some hydrochloric acid in a test tube and add a small spatula load of the solid ionic compound. Look for bubbles of gas. If a gas is released then insert a delivery tube into the test tube and bubble the gas through limewater. If the carbonate ions are present, then the limewater turns couldy when it bubbles pass through it.

If the limewater turns cloudy when bubbles pass through it, then the compound is sodium carbonate.

23
Q

Write an ionic equation including state symbols for each of the following precipitation reaction:

A yellow precipitate is formed when silver nitrate solution is added to a solution of sodium iodide

A

Ag^+ (aq) + I^- (aq) —> AgI (s)

24
Q

Write an ionic equation including state symbols for each of the following precipitation reaction:

A white precipitate is formed when barium chloride solution is added to a solution of potassium sulfate

A

Ba^2+ (aq) + SO4^2- (aq) —> BaSO4 (s)

25
Q

Write an ionic equation including state symbols for each of the following precipitation reaction:

A white precipitate is formed when sodium hydroxide solution is added to a solution of calcium nitrate

A

Ca^2+ (aq) + 2OH^- (aq) —> Ca(OH)2 (s)

(GCSE) Chemistry (24 decks)

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