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

Paper 2 C8 - Chemical Analysis Flashcards

(53 cards)

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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

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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

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

Name the colour produced from a positive lithium flame test

25
Name the colour produced from a positive sodium flame test
Yellow
26
Name the colour produced from a positive potassium flame test
Lilac
27
Name the colour produced from a positive calcium flame test
Orange-red
28
Name the colour produced from a positive copper flame test
Green
29
State why mixtures of ions are difficult to detect using flame tests
Some colours can be masked by others
30
Define precipitate
Insoluble product/solid formed from a reaction
31
State what determines the ion in a metal hydroxide test
Colour of precipitate
32
Write a method for a metal hydroxide test
1. Put unknown solution in test tube 2. Add sodium hydroxide
33
Give the positive result for copper (II) from a metal hydroxide test
Blue precipitate
34
Give the positive result for Iron (II) in a metal hydroxide test
Green precipitate
35
Describe a positive result for Iron (III) in a metal hydroxide test
Brown precipitate
36
Name the three metals that form a white precipitate in a metal hydroxide test
- Aluminium - Calcium - Magnesium
37
Name the metal precipitate that dissolves when excess sodium hydroxide is added
Aluminium
38
Write the word equation for reaction between carbonate ions and acids
carbonate ions + acid --> carbon dioxide + water
39
Write a method to test for carbonate ions, including the positive result
1. Put carbonate into a test tube 2. Add dilute hydrochloric acid 3. Bubble through limewater ---> Limewater turns cloudy
40
Give the positive result for a carbonate ion test
Limewater turns cloudy
41
Name the chemical used to test for sulfate ions
Barium chloride
42
Write method to test for sulfate ions, including the positive result
1. Add sulfate to test tube 2. Add dilute hydrochloric acid 3. Add barium chloride ---> White precipitate will form
43
Name the white precipate formed in a positive sulfate ion test
Barium sulfate
44
Write the word equation for the reaction of magnesium sulfate with barium chloride
magnesium sulfate + barium chloride --> barium sulfate + magnesium chloride
45
Write a method to test for halide ions
1. Add halide to test tube 2. Add nitric acid 3. Add silver nitrate solution
46
Give the result for a positive chloride test
White precipitate
47
Give the result for a positive bromide test
Cream precipitate
48
Give the result for a positive iodide test
Yellow precipitate
49
Name the three precipitates that can form from a positive halide ion test
- Silver chloride - Silver bromide - Silver iodide
50
Give three qualities of instrumental methods (carried out using a machine) that make them better than chemical tests
- Rapid - Sensitive - Accurate
51
Give an example of an instrumental method used to detect/identify elements and compounds
Flame emission spectroscopy
52
Expain how flame emission spectroscopy works
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
State one thing that flame emission spectroscopy can do that flame tests cannot
Detect mixtures of metal ions and their concentrations

Chemistry (Fin) (7 decks)

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