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Chemistry > C12 > Flashcards

C12 Flashcards

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1
Q

What is a pure substance?

A

A substance made from one type of element or compound

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2
Q

What is a mixture?

A

A substance made from two+ DIFFERENT elements or compounds that are not chemically combined

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3
Q

What is a formulation?

A

A mixture that has been specifically designed for a useful product

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4
Q

If a small is pure, will it have a small or large range of boiling/melting point?

A

Small

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5
Q

Name 2 ways the bp and mp of a substance can be used to tell if its pure or not

A
  • looking at range
  • comparing results to a database
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6
Q

What is the test for hydrogen?

A

Hold a lit splint near sample, hydrogen will burn with a squeaky pop

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7
Q

What is the test for oxygen?

A

Hold glowing splint near sample, splint will relight if oxygen is present

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8
Q

What is the test for carbon dioxide?

A

Turns limewater clear to cloudy

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9
Q

What is the test for chlorine?

A

Turns damp blue litmus paper white

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10
Q

In paper chromatography, what is the mobile phase?

A

A solvent such as water

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11
Q

If a compound is more strongly attracted to the mobile phase than the stationary phase, it will _____

A

Travel further up the paper

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12
Q

Why is the baseline drawn in pencil not ink?

A

Ink will dissolve

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13
Q

How do you calculate Rf?

A

Substance travelled by substance/substance travelled by solvent

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14
Q

How many spots will a pure substance produce?

A

1

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15
Q

How can you identify an unknown compound in paper chromatography?

A

Find the Rf then compare it to known substances in a database
Or
Include known samples and see if any spots travel the same distance

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16
Q

How might you carry out a flame test for metal ions?

A
  • dip a nichrome wire loop into a concentrated hydrochloric acid and then heat it to sterilise
  • dip the wire into the unknown sample, then hold it in a roaring flame on a Bunsen burner
  • the colour of the flame tells you if certain metal ions are present
17
Q

What colour flame will sodium produce?

A

Yellow

18
Q

Which metal ion produces a green flame?

A

Copper

19
Q

What colour flame does potassium produce?

A

Lilac

20
Q

Which metal ion produces a crimson flame?

A

Lithium

21
Q

What colour flame does calcium produce?

A

Orange-red

22
Q

To test for carbonate ions, add ___. If ____ is observed, carbonate ions are present.

A

Dilute acid, fizzing

23
Q

___ + acid —-> salt + ____ + _____

A

Metal carbonate
Water
Carbon dioxide

24
Q

____ solution can be used to identify some metal ions

A

sodium hydroxide

25
Q

which ions form a white precipitate with sodium hydroxide solution?

A
  • Al3+
  • Ca2+
  • Mg2+

These ions react with sodium hydroxide to produce insoluble metal hydroxides

26
Q

how can you tell the 3 ions apart?

A

add more NaOH solution-
aluminium precipitate will dissolve, but Ca and Mg precipitates won’t
You can then use a flame test to distinguish between Ca or Mg- Mg has no flame colour

27
Q

What colour precipitate does Cu2+ form?

A

blue

28
Q

What colour precipitate does Fe2+ form?

A

green

29
Q

What colour precipitate does Fe3+ form?

A

brown

30
Q

To test for halides, add ___ and then ___ solution. If a precipitate forms, a halide ion is present

A
  • dilute nitric acid
  • silver nitrate
31
Q

chloride ions form which colour precipitate?

A

white

32
Q

bromide ions form which colour precipitate?

A

cream

33
Q

iodide ions form which colour precipitate?

A

yellow

34
Q

What are some positives of using modern equipment?

A

accurate, sensitive, quick, can work on small samples
but EXPENSIVE

35
Q

Give an example of and explain an instrumental analysis

A

Flame emission spectroscopy:
- metal ions emit unique wavelengths of light when they are heated
- a spectrometer analyses the unique pattern of radiation from a heated sample and compares it to other known line spectra

36
Q

To test for sulfates, add ___ and then ___ solution.

A
  • dilute hydrochloric acid
  • barium chloride
37
Q

In testing for sulfates, if a ___ forms, sulfate ions are present

A

white precipitate

38
Q

Why is hydrochloric acid added when testing for sulfates?

A

To remove any carbonate ions which would form a precipitate with the barium ions

Chemistry (10 decks)

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