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Chemistry > Chemical Analysis > Flashcards

Chemical Analysis Flashcards

1
Q

What is the test for hydrogen and its result?

A

The lit splint test, hydrogen gas burns with a squeaky pop

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1
Q

What is test for carbon dioxide and its result?

A

The gas is bubbled through limewater, if carbon dioxide is present, a white precipitate forms

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2
Q

What is the test for oxygen and its result?

A

Glowing splint placed in the gas will re-light if oxygen is present

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3
Q

What is the test for chlorine and its result?

A

Damp, blue, litmus paper turns white in the presence of chlorine

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4
Q

What is the test for an alkene and its result?

A

Add bromine water, if an alkene is present, it will turn from orange to colourless

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5
Q

What is the test for an acid or an alkali and it’s result?

A

Add an indicator, a colour change will be seen if an acid or alkali is present

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6
Q

What is the test for PH?

A

Add universal indicator and use the colour change to determine the pH

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7
Q

What is the test for an acid?

A

Add a metal carbonate and bubble, the gas produced through limewater. If it was an acid, a white precipitate will form.

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8
Q

What does the word pure mean in relation to substances?

A

A single element or compound not mixed with any other substances

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9
Q

What is a formulation?

A

A mixture of substances designed to be a useful product

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10
Q

What is important to remember about melting points and boiling points in relation to formulations?

A

Formulations do not have a fixed melting point or boiling point, by creating a formulation, the melting point will decrease and the boiling point will increase.

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11
Q

What is chromatography?

A

A process used to separate mixtures

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12
Q

What does chromatography involve?

A

A stationary phase, such as paper and mobile phase such as water. These two phases in separate chemicals based on the solubility in the mobile phase.

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13
Q

What affect solubility have on distance moved up the stationary phase?

A

The more soluble substance is the father. It moves up the chromatogram in a given time.

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14
Q

What is shown on the chromatogram for pure substance?

A

A pure substance will only show one result

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15
Q

How can we compare the chemical compounds that make up different chemicals?

A

Identical chemicals will move at the same rate, and therefore cover the same proportion of the chromatogram

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16
Q

What is the retention factor?

A

It is a quantitative data for chromatography.

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17
Q

What is the equation for the retention factor?

A

Rf= distance moved by chemical/ distance moved by solvent

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18
Q

What happens when electrons absorb energy?

A

Electrons can be promoted to higher energy levels in the atom. Atoms in the state are known as excited.

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19
Q

What happens to excited electrons?

A

Excited electrons will drop back down to their original position when they do this, they release light. Because atoms of different electron arrangement, they give us different frequencies of light. Some of these frequencies of light or in the visible region of the electromagnetic spectrum.

20
Q

What colour flame will a lithium iron produce?

A

Crimson

21
Q

What colour flame do sodium ions produce?

A

Yellow

22
Q

What colour flame will a potassium ion produce?

A

Lilac

23
Q

What colour flame will a calcium ion produce?

A

Orange/Red

24
Q

What colour flame will a copper ion produce?

A

Green

25
Q

What are the four limitations of the flame test?

A
  • Some colours of flame hard to tell from the background
  • Some metals give no visible flame colour
  • Some metals give similar colours of flame
  • A mixture of metals will give a mixture of colours were one is more prominent than the others, hence masking the other colours
26
Q

How do you test for metal ions in solution?

A

By adding sodium hydroxide, the colour of precipitate formed tells us which ions are present

27
Q

What colour precipitate is formed due to iron two ions?

A

Green

28
Q

What colour precipitate is formed due to iron three ions?

A

Orange/Brown

29
Q

What colour precipitate is formed due to copper two ions?

A

Blue

30
Q

What colour precipitate is formed due to calcium ions?

A

White

31
Q

What colour precipitate is formed due to aluminium three ions?

A

White, this precipitate dissolves in excess sodium hydroxide

32
Q

What colour precipitate is formed due to magnesium ions?

A

White

33
Q

What is the test for carbonate ion?

A

Add a dilute acid, if effervescence occurs and common dioxide is being produced then carbonate ion is present

34
Q

What is important to remember about the carbonate test?

A

It must be done at first, as it can give false positives in other ion tests

35
Q

What is the test for sulphate ion?

A
  • Add hydrochloric acid to check for carbonate
  • Add barium chloride, if present, a white precipitate is formed
36
Q

What is the test for halide ions?

A
  • Add nitric acid to check for carbonate
  • Add silver nitrate solution, the colour of precipitate will determine the halide ion present
37
Q

What colour precipitate is formed if chlorine ions are present?

A

White (this precipitate will dissolve in dilute ammonia)

38
Q

What colour precipitate is formed when bromide ions are present?

A

Cream (this precipitate dissolves in concentrated ammonia)

39
Q

What colour precipitate is formed when iodide ions are present?

A

Yellow (this precipitate is insoluble in ammonia)

40
Q

How do we overcome the limitations of the flame test?

A

We use instrumental methods such as flame emission spectroscopy, which uses mechanical methods to scan individual frequencies of light

41
Q

What are the advantages of flame emission spectroscopy?

A
  • Even tiny quantities of a metal can be detected
  • Mixtures can be analysed and compared to known spectra to identify the contents
42
Q

What are the uses of flame emission spectroscopy?

A
  • Detection of trace elements
  • Determination of the composition of stars
43
Q

What is a mass spectrometer?

A

A device that can report the relative mass of compounds

44
Q

What is gas chromatography?

A

A method that separates compound in a mixture and can be used to identify them and give their concentrations

45
Q

What are the advantages of instrumental methods?

A
  • Rapid
  • Sensitive
  • Accurate
46
Q

What is the disadvantage of instrumental methods?

A
  • Expensive equipment
  • Need training to use this equipment
47
Q

What are the advantages of qualitative chemical methods?

A
  • Simple
48
Q

What are the disadvantages of qualitative chemical methods?

A
  • Inaccurate
  • Requires larger samples

Chemistry (5 decks)

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