Chemical Analysis Year 11 Flashcards

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1
Q

define purity and give an example of a pure substance

A

a single element/compound that is NOT mixed with any other substance
ie diamond

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2
Q

give the formula for RF value

A

distance COMPONENT traveled/distance SOLVENT traveled

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3
Q

what should RF value be given to (sf)

A

2sf

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4
Q

what numbers should RF value be between

A

0 and 1

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5
Q

what does the distribution of the components in the sample depend on

A

relative attraction to the paper and solvent

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6
Q

define a formulation

A

PURE substances carefully mixed in specific proportions to have desired propertied

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7
Q

what can RF values be used for

A

to identify substances in a solvent

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8
Q

comment on RF values from substance to substance

A

different compounds have different RF values

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9
Q

what is the gas test for hydrogen

A

lighted splint emits a squeaky pop

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10
Q

what is the gas test for oxygen

A

glowing spilt will relight

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11
Q

what is the gas test for CO2

A

turns limewater from clear to cloudy

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12
Q

what is the gas test for chlorine

A

turns BLUE litmus paper RED the bleaches it

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13
Q

describe the importance of gas tests

A

must identify substances present for:

  • safety
  • helps to identify substances present
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14
Q

what is the trend of melting/ boiling points for pure substances

A

the all have very specific temperatures

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15
Q

give substances where purity is especially importants

A
  • medication
  • baby food
  • cosmetics
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16
Q

give a possible suggestion of a melting point of a pure substance

A

88-89*C

17
Q

give examples of formulations

A
  • alloys
  • fertilisers
  • gold jewellery
18
Q

state the speed at which substances with a stronger attraction to the paper will travel

A

slower and move less far up the paper

19
Q

state the speed at which substances with a weaker attraction to the paper will travel

A

faster and move further up the paper

20
Q

what is RF value

A

ratio of distance moved by substances to solvents

21
Q

how could RF values be different if different solvents/stationary phases are used

A

the substances could have a stronger/ weaker attraction to the stationary phase so they would move quicker/slower therefore RF value is altered

22
Q

how could RF values be different if different solvents are used

A

solvents could be less soluble so wouldn’t dissolve all of the compounds

23
Q

what are the two phases called in chromotography

A

-

24
Q

in paper chromatography, how many spots will a pure substance form on the paper

A

-

25
Q

give the formula for working out the Rf value of a substance

A

-

26
Q

how can you test if a gas in a test tube is oxygen?

A

-

27
Q

describe how paper chromotography works to separate mixtures

A

-

28
Q

what colour does litmus paper turn in the presence of chlorine

A
  • white (if it goes red for a moment its bc chlorine is acidic)
29
Q

would you expect the Rf value of a substance to change if you changed the solvent in the chromatography experiment. why?

A

-

30
Q

a student collects gas given off during a reaction & bubbles go through limewater. the limewater goes cloudy. identify the gas produced

A
  • carbon dioxide