Chap 5 - Physical, chemical and separation techniques Flashcards

1
Q

define physical change

A

involves a change in substance’s form

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2
Q

define chemical change

A

involves making a new substance and change in energy

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3
Q

what measures time and units

A

-stop watch
-seconds

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4
Q

what measures temperature and units

A

-thermometer
-degrees Celsius

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5
Q

what measures mass and units

A

-mass balance
-grams

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6
Q

what measures volume in liquid and units-1

A

-burette
-cm^3

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7
Q

what measures volume in liquid and units- 2

A

-volumetric pipette
-cm^3

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8
Q

what measures volume in liquid and gas and units

A

-measuring cylinder
-cm^3

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9
Q

what measures volume in gas and units

A

-GAS syringe
-cm^3

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10
Q

define pure

A

a substance that contains a single element or compound, not mixed with any other substances

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11
Q

define impure

A

a substance that contains more than 1 element or compound, mixed with other substances

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12
Q

define solvent

A

substance that dissolves a solute

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13
Q

define solute

A

a substance that is dissolves in a solvent

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14
Q

define solution

A

mixture that is made up of 1 or more substances

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15
Q

define mixture

A

contains 2 or more substances not chemically combined

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16
Q

define votality

A

how easily a substance evaporates (changes from liquid to gas)

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17
Q

define solubility

A

how easily a substance dissolves

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18
Q

is a solution a new product

A

no

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19
Q

define saturated solution

A

solution containing maximum concentration of a solute dissolved in a solvent at a given temp.
(no more solute can dissolve in it)

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20
Q

opposite of saturated

A

diluted

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21
Q

define residue

A

a substance that remains after distillation, evaporation or filtration

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22
Q

define crystallisation

A

when a liquids that contains soluble solute is evaporated to leave the soluble solute behind

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23
Q

define filtrate

A

solution at pass through a filter paper

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24
Q

explain diluted, concentrated, saturated

A

diluted:
-little solute
concentrated:
-moderate solute
saturated:
-max solute

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25
Q

what must the solute be for filtration and why

A

insoluble so it’s too big to pass through the holes in the filter paper

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26
Q

names 6 separation techniques

A

-simple distillation
-fractional distillation
-filtration
-evaporation
-crystallisation
-chromatography

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27
Q

define evaporation

A

turning the liquid into gas to be lost from the substance using heat

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28
Q

define filtration

A

passing solution over a filter paper and collecting the filtrate

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29
Q

define immiscible and miscible

A

-immiscible- liquids that don’t mix
-miscible- liquids that mix

30
Q

how to get
-insoluble solute from mixture of soluble and insoluble solute/ solution with insoluble solute

A

filtration

31
Q

how to get solute (soluble or insoluble) from solution

A

evaporation

32
Q

how to separate 2 immiscible liquids

A

separating funnel

33
Q

how to
-at least 2 miscible liquids
-solutions with liquids that have close boiling points to each other

A

-fractional distillation

34
Q

how to get solvent from soluble solute

A

-simple distillation

35
Q

how to separate 2 or more soluble solutes

A

-paper chromatography

36
Q

why does filtrations work to separate insoluble solute from solute

A

insoluble solute cannot pass through filter paper and is left as an residue. soluble solutes can pass through the paper

37
Q

why does evaporation work to get a solute from a solution

A

the solvent must have a lower boiling point than the solute

38
Q

why does a separating funnel work to separate 2 immiscible liquids

A

-there is a difference in density

39
Q

why does fractional distillation work to separate 2 miscible liquids

A

there is a difference in boiling points between the liquids

40
Q

why does simple distillation work to separate solvent from solute

A

there is a difference in boiling points between solvent and solute

41
Q

define chromatography

A

method of separating mixtures of soluble substances

42
Q

define stationary phase

A

the paper in paper chromatography

43
Q

define a chromatogram

A

result of separating the components of a mixture by chromatography

43
Q

define the mobile phase

A

solvent in paper chromatography

44
Q

define Rf value

A

retention factor

45
Q

formula for Rf value

A

distance of travelled by solvent (solvent front)
(in decimal)

46
Q

define solvent front

A

-furthest point the solvent travels
-for calculating Rf value

47
Q

define baseline

A

line that is drawn in an insoluble substance and where the inks are placed

48
Q

meaning of composition

A

what it’s made up of

49
Q

the more it’s attracted to stationary phase, the ?

A

closer it is to baseline

50
Q

the more soluble, the ?

A

further it travels up the paper

51
Q

how much must the solvent be

A

below the baseline but touches the paper

52
Q

what is the baseline drawn in and why

A

-pencil
-it is insoluble so it doesn’t travel up the paper

53
Q

where do you measure how far the solute travelled

A

the middle of the spot

54
Q

what happens if the solvent is above the baseline

A

solutes will just dissolve in liquid and not move up

55
Q

where is the water put from in the condenser of distillation

A

the lower part down the condenser

56
Q

3 ways purity of a substance can be assessed

A

-melting point
-boiling point
-chromatography

57
Q

what does impurities do

A

-lower melting point
-increase boiling point
(melts over a greater range)

58
Q

what is the difference between melting and boiling points of pure and impure substances

A

pure- has a sharp melting/ boiling point
impure- melts/ boils over a range

59
Q

how many spots will a pure and impure substance have on chromatography

A

pure- 1
impure- more than 1

60
Q

describe how to obtain a pure dry sample of a substance from a chromatogram

A

-isolate substance
-dissolve in solvent
-evaporate solvent

61
Q

note: learn how to draw apparatuses

A
62
Q

do permanent markers work for chromatography

A

no, it’s insoluble

63
Q

-substance melts at 96 but melts completely at 113.
-date book says melting point of substance is 116.
-explain is substance is impure or not

A

-impure
-melts over a range
-melting point is different to data book value.

64
Q

describe how to get a pure dry sample of a compound from a chromatogram

A

-isolate the substance
-dissolve the compound in a solvent
-evaporate the solvent

65
Q

explain if a substance is impure or pure

A

-range it melts over
-different from data book value

66
Q

2 processes to obtain pure sodium chloride from mixture with insoluble sulfer and sodium chloride in water

A

filtration and crystaillisation

67
Q

2 processes to separate water from insoluble chalk and soluble salt

A

filtration and crystalisation

67
Q

apparatus to measure volume of gas

A

gas syringe

68
Q

-colorings S,T and U are -soluble
-use chromatography in candy to find them
measurements?

A

-height of each spot and height of solvent front
-compare Rf values of colourings and candy

68
Q

-colorings S,T and U are -soluble
-use chromatography in candy to find them
method?

A

-crush candy and dissolve in solvent
-pencil line on paper
-add each colours and sweet solution to paper
-remove paper before solvent reaches the top
-mark solvent line and find Rf value

69
Q

-colorings S,T and U are -soluble
-use chromatography in candy to find them
use of results?

A

-if candy spots are same height up paper as S, T, S, then substances are in the candy
-if same ratio of spot distance to solvent front distance (Rf value), substance is in candy