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A Chemistry IGCSE course > Chemical tests > Flashcards

Chemical tests Flashcards

1
Q

What is the test and the result for:

Carbonate ion?

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
  • If the limewater turns cloudy, carbonate is present
  • CO3 + 2HCl → Cl2 + CO2 + H2O, with one of the reactant being carbon dioxide, which reacts with limewater to form calcium carbonate which is an insoluble solid
  • Ca(OH)2 + CO2 → CaCO3 + H2O
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2
Q

What is the test for:

Halide ion

A
  • Dissolve a small amount of the solid ionic compound in deionised water (about 3 cm depth).
  • Add a few drops of nitric acid
  • Add 1 cm depth of silver nitrate solution
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3
Q

What is the test and result for:

Sulfate ion?

A
  • Dissolve a small amount of the solid ionic compound in deionised water(about 3cm depth)
  • Add a few drops of hydrochloric acid
  • Add 1cm depth of barium chloride solution
  • A white precipitate is formed if sulfate ion is present
  • SO2-4 + Ba2+ -> BaSO4
    Sulfate white solid
    ion precipitate
    (High 2- sign low 4 sign)
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4
Q

What is the result for:

Halide ion test?

A
  • Chloride ion - white
  • Bromide ion - creamy
  • Iodide ion - yellow
  • Silver nitrate is AgNO3
  • Ag+ + Cl- –> AgCl (white precipitate)
  • Ag+ + I- –> AgI (yellow precipitate)
  • Ag+ + Br- –> AgBr (creamy precipitate)
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5
Q

What is the chemical test for the:

Flame test

A
  • Turn on a bunsen burner using a match, and then put it on the roaring flame.
  • Clean a platinum or nichrome wire loop by pouring it into HCl
  • Put the wire into the bunsen burner, to make sure that there is no flame colour
  • Put the wire into the substance that is to be tested
  • Put the wire into the bunsen burner and record the flame colour
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6
Q

What are the results of:

Different Cations in flame test?

A

Cation name Cation formula Colour of flame
Lithium Li+ Red
Sodium Na+ Yellow
Potassium K+ Lilac
Calcium Ca2+ Orange-red
Copper Cu2+ Green-blue

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7
Q

What is:

Anion

A

Negatively charged ion

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8
Q

What is a:

Cation

A

Positively charged ion

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9
Q

What is the test for:

Carbon dioxide

A
  1. Attach a tube from the sample that is to be tested to limewater
  2. If the limewater turns cloudy, carbon dioxide is present
  3. This is because the precipitate calcium carbonate is made
  4. CO2 + Ca(OH)2 -> CaCO3 + H2O, which is how the calcium carbonate is made in the reaction
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10
Q

What is the test for:

Hydrogen

A
  1. Place a lit splint in the test tube that is to be tested
  2. If there is a squeaky pop, hydrogen is present
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11
Q

What is the test for:

Oxygen

A
  1. Place a glowing splint in a test tube of the substance that is to be tested
  2. If the splint relights, oxygen is present
  3. This is because oxygen is in the fire triangle
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12
Q

What is the test for:

Ammonia

A

Damp red litmus paper in water. Put the solution that is tested in a test tube. Heat the solution with a Bunsen burner to make the solution evaporate and place the litmus paper above the test tube. If Ammonia is present, the red litmus paper will turn blue. This is because Ammonia reacts with water to make ammonium hydroxide which has hydroxide which will turn litmus paper blue.

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13
Q

What is the test for:

Chlorine

A

Put the gas that is to be tested in a test tube. Place a damp blue litmus paper above the test tube. If the litmus paper turns red then white, chlorine gas is present.

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14
Q

What is the physical test for:

Water

A

Water will boil at 100℃
This can be tested using distillation

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15
Q

What is the chemical test for:

Water

A

Anhydrous copper sulphate turns blue in the presence of water

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16
Q

What is the test and result and why for:

Several cations

(not flame test)

A

Testing for cations method 2:
Place 5cm3 of copper in one test tube
Place 5cm3 of iron (II) solution in another test tube
Place 5cm3 of Iron (III) solution in a third test tube
Add sodium hydroxide (5 drops using pipette)
Observe and record in a suitable table
Certain metal ions will react with the hydroxide to form a precipitate
The colour of this precipitate identifies the metal ion

Cation Colour of precipitate
Copper sulphate (Cu2+) Blue colour
Iron(II) (Fe2+) Green
Iron (III) (Fe3+) Orange

Cu2+ + 2OH- -> Cu(OH)2 (s)
Fe2+ + 2OH- -> Fe(OH)2 (s)
Fe3+ + 3OH- -> Fe(OH)3 (s)

17
Q

What is the test for:

Ammonium

A

NH4(+) + OH(-) –> NH3 + H2O which forms ammonia which can be tested with damp red litmus paper
NH3 + H20 –> NH4OH this is alkaline and will turn damp red litmus paper blue

18
Q

What is the formula for ammonium nitrate

A

NH4NO3

A Chemistry IGCSE course (14 decks)

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