Chemical Analysis Flashcards

(63 cards)

1
Q

How do you test for chlorine (gas)?

A

Bleach damp litmus paper - turning it white

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2
Q

How do you test for oxygen?

A

A glowing splint relit when put inside a test tube containing oxygen

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3
Q

How do you test for hydrogen?

A

A lit splint causes a squeaky pop when placed at end of a test tube containing hydrogen

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4
Q

How do you test for carbon dioxide?

A

Limewater turns cloudy when carbon dioxide bubbled through

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5
Q

What are flame tests used to identify?

A

Some metal ions that burn with distinctive flame

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6
Q

What metal makes a crimson flame?

A

Lithium

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7
Q

What metal makes a yellow flame?

A

Sodium

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8
Q

What metal makes a lilac flame?

A

Potassium

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9
Q

What metal makes a orange-red flame?

A

Calcium

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10
Q

What metal makes a green flame?

A

Copper

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11
Q

What colour flame for lithium?

A

Crimson flame

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12
Q

What colour flame for sodium?

A

Yellow flame

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13
Q

What colour flame for potassium?

A

Lilac flame

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14
Q

What colour flame for calcium?

A

Orange-red flame

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15
Q

What colour flame for copper?

A

Green flame

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16
Q

What is the problem of using a sample containing a mixture of metal ions?

A

Some flame colours might be masked by stronger ions

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17
Q

What solution helps identify some metal ions?

A

Sodium hydroxide solution

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18
Q

What colour precipitate does calcium form?

A

White precipitate - check using flame test

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19
Q

What colour precipitate does copper form?

A

Blue precipitate

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20
Q

What colour precipitate does magnesium form?

A

White precipitate

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21
Q

What colour precipitate does aluminium form?

A

White precipitate - redissolves in excess to form colourless solution

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22
Q

What colour precipitate does iron (II) form?

A

Green precipitate

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23
Q

What colour precipitate does iron (III) form?

A

Brown precipitate

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24
Q

Which metal ion forms a blue precipitate?

A

Copper

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25
Which metal ion forms a white precipitate and can be checked using a flame test?
Calcium
26
Which metal ion forms a white precipitate?
Magnesium
27
Which metal ion forms a white precipitate that redissolves in excess to form a colourless solution?
Aluminium
28
Which metal ion forms a green precipitate?
Iron (II)
29
Which metal ion forms a brown precipitate?
Iron (III)
30
How do you test for carbonates?
Add dilute acid to solution Connect test tube to limewater Limewater turns cloudy if carbonate ions present - carbon dioxide released
31
What do you add to a solution to test for carbonates?
Dilute acid
32
What do you connect the solution to to test for carbonates?
Limewater
33
Why do you connect the solution to limewater when testing for carbonates?
To see if the limewater turns cloudy, to see if carbon dioxide is produced
34
How do you test for sulfates?
Add dilute hydrochloric acid Add barium chloride solution A white precipitate of barium sulfate will form if sulfate ions present
35
What do you add to the solution to test for sulfates?
Dilute hydrochloric acid then barium chloride solution
36
What do you add to a solution to test for a halide ion?
Dilute nitric acid and then silver nitrate solution
37
How do you test for a halide ion in a solution?
Add dilute nitric acid Add silver nitrate solution See colour of precipitate if formed
38
What colour precipitate does chloride form when testing for halides?
White precipitate - silver chloride
39
What colour precipitate does bromide form when testing for halides?
Cream precipitate - silver bromide
40
What colour precipitate does iodide form when testing for halides?
Yellow precipitate - silver iodide
41
What halide ion is present if yellow precipitate formed?
Iodide
42
What halide ion is present if cream precipitate formed?
Bromide
43
What halide ion is present if white precipitate formed?
Chloride
44
Why are instrumental methods a great way to identify elements and compounds?
They are accurate, sensitive and rapid
45
What is flame emission spectroscopy used to analyse?
Metals ions in a solution
46
How does flame emission spectroscopy work?
Sample put into a flame When ions heat up, the electrons become excited When electrons drop back to normal level of energy, they transfer energy as light Light is passed through spectroscope Spectroscope detects different wavelengths of light Produces line spectrum
47
Why do different ions emit different wavelengths of light during flame emission spectroscopy?
Because each ion has a different charge and electron arrangement
48
Why is flame emission spectroscopy more useful than flame tests?
Flame emission spectroscopy can be used to detect different ions in mixtures - more useful than flame tests
49
What is meant by purity in chemistry?
A singe element or compound
50
What type of elements/compounds melt and boil at specific temperatures?
Pure elements and compounds
51
What is the mobile phase in chromatography?
Where the molecules can move
52
What is the stationary phase in chromatography?
Where the molecules can't move
53
The _____ phase moves through the _________ phase and anything dissolved in the ______ phase moves with it
Mobile Stationary Mobile
54
Chemicals that spend more time in the ______ phase than the ________ phase, will move further through the _________ phase
Mobile Stationary Stationary
55
What do components on a mixture normally separate through during chromatography?
The stationary phase
56
How many spots will be formed by a pure substance during chromatography?
1
57
The amount of time the molecules spend in each phase depends on:
How soluble they are in the solvent | How attracted they are to the paper
58
Molecules with a higher solubility in the solvent and which are less attracted to the pare will spend more time in the ______ phase
Mobile
59
If a dye has a higher attraction to the mobile phase, they move...
Further up
60
If a dye has a stronger attraction to the stationary phase, they move...
Don't move as much
61
What is the Rf value?
The ration between the distance travelled by the dissolved substance and the distance travelled b the solvent
62
Rf =
Distance travelled by substance ----------------------------------------------- Distance travelled by solvent
63
The further up the stationary phase you move, the _______ the Rf value
Larger