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Chemistry (Fin) > Paper 2 C8 - Chemical Analysis > Flashcards

Paper 2 C8 - Chemical Analysis Flashcards

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1
Q

Define pure substance

A

A single element or compound (not mixed in with any other substance)

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2
Q

Name two things that can be used to distinguish between pure and impure substances

A
  • Melting point
  • Boiling point
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3
Q

Explain how melting and boiling points can be used to distinguish between pure and impure substances

A
  • Pure substances have a specific boiling and melting point
  • Impure substances melt/boil over a range of temperatures
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4
Q

Impure substances normally melt at a _________ temperature than pure substances.

A

Lower

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5
Q

Define formulation

A

Mixture made for a specific purpose

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6
Q

State how formulations are made

A

Mixing specific amounts of chemicals to get certain properties

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7
Q

Give five examples of formulations

A

Any five from:
- Alloys
- Paint
- Medicine
- Fuels
- Fertilisers
- Cleaning agents
- Foods

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8
Q

Outline the purpose of chromatography

A

Separate mixtures into their components and identify them

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9
Q

Name the two phases in chromatography

A
  • Stationary phase
  • Mobile phase
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10
Q

Identify the stationary phase in chromatography

A

The chromatography paper

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11
Q

Identify the mobile phase in chromatography

A

The solvent

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12
Q

Describe the relationship between the solubility of a substance and how far it moves up the paper in chromatography

A

The more soluble the substance, the further up the paper it moves (and vice versa)

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13
Q

Name the value that is used to identify substances in chromatography

A

Rf value

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14
Q

Give the equation used to calculate the Rf value of a substance

A

distance travelled by substance/distance travelled by solvent

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15
Q

Outline the difference between the appearance of a mixture and a pure substance on chromatography paper

A
  • Mixture will produce multiple spots
  • Pure substance will only produce one spot
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16
Q

Write a method for chromatography

A
  1. Draw pencil start line on chromatography paper
  2. Place spot of [mixture] on start line
  3. Place [solvent] in a beaker
  4. Place chromatography paper in solvent
    –> [solvent] should be below start line
  5. Use a lid
  6. Wait for solvent to travel up chromatography paper
  7. Mark solvent front
  8. Dry the chromatography paper
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17
Q

Write a method to test for hydrogen, including the positive result

A

Place a burning splint at the open end of a test tube of the gas
—> Will burn with a squeaky pop

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18
Q

Write a method to test for oxygen, including the positive result

A

Place a glowing splint inside a test tube of the gas
—> Splint will relight

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19
Q

Write a method to test for carbon dioxide, including the positive result

A

Bubble through limewater
—> Limewater will turn cloudy

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20
Q

Write a method to test for chlorine, including the positive result

A

Place damp litmus paper into a test tube of the gas
—> Litmus will be bleached white

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21
Q

Name the two methods used to identify metal ions

A
  • Flame test
  • Metal hydroxide test
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22
Q

Write a method for a flame test

A
  1. Clean wire (using HCl)
  2. Dip wire into unknown compound
  3. Place in roaring (blue) flame
  4. Observe the colour
23
Q

Name the 5 metal compounds that can be detected through flame tests

A
  • Lithium
  • Sodium
  • Potassium
  • Calcium
  • Copper
    (LSPCC)
24
Q

Name the colour produced from a positive lithium flame test

A

Crimson

25
Q

Name the colour produced from a positive sodium flame test

A

Yellow

26
Q

Name the colour produced from a positive potassium flame test

A

Lilac

27
Q

Name the colour produced from a positive calcium flame test

A

Orange-red

28
Q

Name the colour produced from a positive copper flame test

A

Green

29
Q

State why mixtures of ions are difficult to detect using flame tests

A

Some colours can be masked by others

30
Q

Define precipitate

A

Insoluble product/solid formed from a reaction

31
Q

State what determines the ion in a metal hydroxide test

A

Colour of precipitate

32
Q

Write a method for a metal hydroxide test

A
  1. Put unknown solution in test tube
  2. Add sodium hydroxide
33
Q

Give the positive result for copper (II) from a metal hydroxide test

A

Blue precipitate

34
Q

Give the positive result for Iron (II) in a metal hydroxide test

A

Green precipitate

35
Q

Describe a positive result for Iron (III) in a metal hydroxide test

A

Brown precipitate

36
Q

Name the three metals that form a white precipitate in a metal hydroxide test

A
  • Aluminium
  • Calcium
  • Magnesium
37
Q

Name the metal precipitate that dissolves when excess sodium hydroxide is added

A

Aluminium

38
Q

Write the word equation for reaction between carbonate ions and acids

A

carbonate ions + acid –> carbon dioxide + water

39
Q

Write a method to test for carbonate ions, including the positive result

A
  1. Put carbonate into a test tube
  2. Add dilute hydrochloric acid
  3. Bubble through limewater
    —> Limewater turns cloudy
40
Q

Give the positive result for a carbonate ion test

A

Limewater turns cloudy

41
Q

Name the chemical used to test for sulfate ions

A

Barium chloride

42
Q

Write method to test for sulfate ions, including the positive result

A
  1. Add sulfate to test tube
  2. Add dilute hydrochloric acid
  3. Add barium chloride
    —> White precipitate will form
43
Q

Name the white precipate formed in a positive sulfate ion test

A

Barium sulfate

44
Q

Write the word equation for the reaction of magnesium sulfate with barium chloride

A

magnesium sulfate + barium chloride –> barium sulfate + magnesium chloride

45
Q

Write a method to test for halide ions

A
  1. Add halide to test tube
  2. Add nitric acid
  3. Add silver nitrate solution
46
Q

Give the result for a positive chloride test

A

White precipitate

47
Q

Give the result for a positive bromide test

A

Cream precipitate

48
Q

Give the result for a positive iodide test

A

Yellow precipitate

49
Q

Name the three precipitates that can form from a positive halide ion test

A
  • Silver chloride
  • Silver bromide
  • Silver iodide
50
Q

Give three qualities of instrumental methods (carried out using a machine) that make them better than chemical tests

A
  • Rapid
  • Sensitive
  • Accurate
51
Q

Give an example of an instrumental method used to detect/identify elements and compounds

A

Flame emission spectroscopy

52
Q

Expain how flame emission spectroscopy works

A
  1. Sample is placed into a flame
  2. Light given off is passed through a spectroscope
  3. Spectroscope splits light up into different wavelengths
  4. Each ion produces a different line spectrum
53
Q

State one thing that flame emission spectroscopy can do that flame tests cannot

A

Detect mixtures of metal ions and their concentrations

Chemistry (Fin) (7 decks)

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