Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

chemistry > chemical analysis > Flashcards

chemical analysis Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards
1
Q

define pure substance

A

single element / compound not mixed with any other substance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how to check if a substance is pure or a mixture(impure)

A

heat substance
measure heating point
measure boiling point
if its fixed, the substance is pure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Pure ……… and ……. melt and boil at ……. temperatures. Melting point and boiling point …. can be used to
distinguish ….. substances from mixtures.

A

Pure elements and compounds melt and boil at specific
temperatures. Melting point and boiling point data can be used to
distinguish pure substances from mixtures.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how can you tell if a substance is a mixture

A

if the substance melts / boils over a range of temperatures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is a pure substance in everyday language

A

a substance that has nothing else added to it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

example of a pure substance in everyday life

A

pure milk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is a formulation

A

complex mixture , designed to be a useful product

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

formulations are made by mixing

A

carefully measured components so the product has the properties we need

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

5 examples of formulations

A

fuels,
cleaning agents,
paints,
medicines,
alloys,
fertilisers
foods.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

all separation techniques are …..

A

physical processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what does it mean if something is a physical process

A

doesn’t involve physical reactions
no new substances are made

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what does paper chromatography do

A

separate substances based in different solubilities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

how to carry out chromatography

A

pencil line along bottom of chromatography paper
dot of #1 colour on line
#2 dot next to it
bottom of paper in solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what happens in chromatography

A

solvent makes way up paper and
dissolves ink in 2 coloured dots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what phase is the paper, why

A

paper- stationary phase, doesn’t move

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what phase is the solvent, why

A

solvent- mobile phase, it moves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

why does paper chromatography work

A

each chemical in mixture is attracted to paper to a different extent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what will happen to chemicals that are strongly attracted to stationary phase (paper)

A

they wont move very far

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what will happen to chemicals that are weakly attracted to stationary phase (paper)

A

move further up the paper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

a pure chemical will produce…..

A

a single spot in all solvents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

the chemicals in a mixture may

A

separate into different spots depending on solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

why do we draw starting line in pencil

A

pen ink would move up paper with solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

why do we draw starting line in pencil

A

pen ink would move up paper with solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

why do we draw starting line in pencil

A

pen ink would move up paper with solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

RP- paper chromatography
describe in depth
6 key points
4 add on points

A

**use ruler- draw horizontal pencil line 2 cm from edge of paper
-X no. of pencil spots, equal intervals, minimum 1 cm away from sides of paper
**glass capillary tube- put small spot of colouring on each pencil spot.
-small spots- stop colours running into eachother
-label spots in pencil
**pour 1cm squared water in beaker
**tape paper to glass rod so bottom of paper dips into water
**remove paper when water is around 3/4 up it
-use pencil, mark point where water reached
**hang paper to dry
***calculate RF value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

how do you calculate rf value

A

distance moved by chemical/ distance moved by solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

how do you measure distance of chemical

A

pencil line to centre of dot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is the solvent front

A

distance moved by solvent

28
Q

how would you find out identity of the chemical

A

look up rf value in database

29
Q

you want to identify chemical but several other chemicals have same rf value. what do u do

A

repeat using different solvent to narrow down

30
Q

what is another solvent u can use in chromatography

A

ethanol

31
Q

safety precaution

A

don’t put chemical in eye- irritation

32
Q

3 important points to remember in required practical for chromotography

A

pencil line with ink above water
paper x touch side of beaker
use lid

33
Q

why is pencil line with ink spots drawn above the water

A

otherwise water will wash off ink

34
Q

why is paper not allowed to touch walls of beaker

A

this will interfere with how water moves

35
Q

why do we use a lid

A

to prevent evaporation

36
Q

what happens once practical is set up

A

water moves up beaker and carries up colours

37
Q

when do we remove paper

A

when water is 3/4 up

38
Q

2 things we do after we remove the paper

A

draw line where water reached
hang up to dry

39
Q

how do you know if chemical hasn’t been analysed before

A

x rf value on data base

40
Q

what would you do if chemical hasn’t been analysed before

A

carry out further analysis to identify it

41
Q

how to test for hydrogen

A

hold burning splint at end of open test tube of gas

42
Q

positive test for hydrogen

A

hydrogen burns rapidlt with squeaky pop sound

43
Q

The test for …… uses a burning ….. held at the open end of
a test tube of the gas. Hydrogen burns ….. with … sound.

A

The test for hydrogen uses a burning splint held at the open end of
a test tube of the gas. Hydrogen burns rapidly with a pop sound.

44
Q

how to test for oxygen

A

glowing splint inserted into test tube of gas

45
Q

positive test for oxygen

A

splint bursts into flames (relights)

46
Q

how to test for co2

A

gas shaken with / bubbled through limewater

47
Q

what is limewater

A

aqueous solution of calcium hydroxide
(calcium hydroxide dissolved in water)

48
Q

positive test for co2

A

repeat bubbling/ shaking gas with limewater and turn s cloudy

49
Q

how to test for chlorine

A

insert damp litmus paper into test tube of gas

50
Q

positive test for chlorine

A

chlorine bleaches litmus paper. turns it white

51
Q

what are flame tests used for

A

identifying an unknown compound
which contain a metal ion

52
Q

how to carry out flame test
2 steps

A

small amount of chemical onto wire on a handle.
put end in blue bunsen burner flame

53
Q

what is the colour of the flame used for

A

to identify the metal ion present

54
Q

what colour flame produced by lithium

A

crimson

55
Q

what colour flame produced by sodium

A

yellow

56
Q

what colour flame produced by potassium

A

lilac

57
Q

what colour produced by calcium

A

orange red flame

58
Q

what colour flame produced by copper

A

green

59
Q

problem with using flame test to identify metal ion

A

colour hard to distinguish
especially if low concentration of metal ion

some samples contain mixture of metal ions, masking colour of flame

60
Q

what can be used instead of flame tests

A

flame emission spectroscopy

61
Q

what happens in flame emission spectroscopy
3 points

A

. sample of metal ion put into a flame
. light given out passed into spectroscope
. spectroscope converts light into line spectrum

62
Q

what is flame emmision spectroscopy used for.

A

analysing metal ions in a solution

63
Q

the line spectrum can be
analysed to….

A

identify the metal ions in the solution
+
measure concentration of metal ions

64
Q

what is important to know about the positions of the lines in the spectrum

A

the position of the lines are specific for a given metal ion

65
Q

what does more intense lines mean in flame emission spectroscopy

A

higher concentration

66
Q

hat does instrumental method mean

A

carried out by a machine

67
Q

3 advantages of instrumental methods

A

rapid
sensitive
accurate

chemistry (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions