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Chemistry > C2.1 separating techniques > Flashcards

C2.1 separating techniques Flashcards

(60 cards)

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1
Q

what is the relative atomic mass?

A

(Ar) is the average mass of an atom of an element compared to 1/12 of the mass of a 12c atom

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2
Q

what is the relative formular mass?

A

(Mr) the average mass of a unit of the substances compared to 1/12 of the mass of a carbon -12 atom

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3
Q

what is the relative formular mass of CO2?

A

12 x 1=12
16 x 2=32
12+32=44

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4
Q

what is the relative formular mass of NaHCO3?

A

sodium-23 x 1=23
hydrogen-1 x 1=1
carbon-12 x 1=12
oxygen-16 x 3=48
48+1+12+48=84

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5
Q

what is the relative formular mass for magnesium oxide?

A

MgO
magnesium=24.3 x 1=24.3
oxygen=16 x 1=16
16+24.3=40.3

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6
Q

what is the relative formular mass for calcium sulphate?

A

CaSO4
calcium=40.1 x 1=40.1
sulphate=32.1 x 1=32.1
oxygen=16 x 4=64
64+32.1+40.1=136.2

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7
Q

what is aluminium oxide in chemical form?

A

Al2O3

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8
Q

what is magnesium chloride in chemical form?

A

MgCl2

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9
Q

what is nitric acid in chemical form?

A

HNO3

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10
Q

what is an empirical formular?

A

the simplest whole number ratio of atoms in a compound

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11
Q

if the molecular formula is NO2 what is the empirical formula?

A

NO2

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12
Q

if the molecular formula is C2H6O2 what is the empirical formula?

A

CH3O

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13
Q

if the molecular formula is N2H2 what is the empirical formula?

A

NH

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14
Q

if the molecular formula is C5H10 what is the empirical formula?

A

CH2

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15
Q

what does the chemical formula show?

A

how many atoms of each element there are in a unit of substances

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16
Q

what does a pure substance consist of?

A

one element or compound

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17
Q

why is a mixture not a pure substance?

A

because mixtures contain more than one element or compound

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18
Q

what can the melting and boiling point be used to determine?

A

the purity of a substance

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19
Q

what type of melting/boiling point will a pure substance have and why?

A

it will have a very specific melting/boiling point as it will only contain one compound/element

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20
Q

what type of melting/boiling point will an impure substance have and why?

A

it will have wide melting/boiling points as they contain different elements/compounds

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21
Q

are elements bonded to each other?
(mixture of elements and compounds)

A

mixture of elements-no
compounds-yes

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22
Q

what are the properties the same?
(mixture of elements and compounds)

A

mixture of elements-no
compounds-yes

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23
Q

does it have a fixed ratio?
(mixture of elements and compounds)

A

mixture of elements-no
compounds-yes

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24
Q

is it hard to separate the elements and why?
(mixture of elements and compounds)

A

mixture of elements -no as the atoms aren’t bonded together
compounds-yes as the atoms are bonded together

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25
what is a formulation?
a mixture with a fix ratio of substances mixed
26
what is purity?
a measure of how pure a substance is
27
what is a mixture?
2 or more substances not chemically bonded together
28
what is impure?
a substance made up of more than one different element or substance
29
what is pure?
something that only contains one type of element or substance
30
what is a solution?
a mixture formed when a solute dissolves in a solvent
31
what equipment is used in filtration?
filter paper funnel residue conical flask filtrate
32
what is filtration?
a method to separate a liquid from an insoluble solid as well as a solution from a solid that is mixed with it but not dissolved
33
how does the filter let some tings through and not others?
it works because filter paper has tiny microscopic holes. when filter a mixture of sand and water, the water will pass through because the molecules are small enough to fit through the holes. the large grains of insoluble sand cannot and therefore water will pass through as a filtrate and the sand will stay in the filter paper as a residue
34
what does a solute and a solvent make?
a solution
35
what is the solute?
a solid that dissolves
36
what is the solvent?
what the solute dissolves in
37
when is a solution is made?
when then the solute and solvent mix together
38
what type of crystals are made during a slow evaporation?
large crystals
39
what type of crystals are made during fast evaporation?
small crystals
40
what is a saturated solution?
a solution that contains the maximum amount of solute that is capable of being dissolved at a specific temperature
41
what can you use to separate water from a salt and sand mixture?
use filtration to separate the sand from the saltwater and then use crystallisation to separate salt crystals from the water
42
what is evaporation?
when particles leave a liquid and turn into a gas
43
what is distillation?
when a solution is evaporated and then condensed
44
what can distillation be used for?
to separate solvents from solutions like water from inky water
45
what two physical processes are used in simple distillation?
evaporation and condensation
46
what properties of a substance helps to separate mixture of two liquids?
different boiling points
47
how does different boiling points help with the separation of a mixture of two liquids?
so that the one with the lower boiling point evaporates and is separated from the other liquid
48
describe the distillation of salty water?
the mixture of salt particles and water is heated and since water has a lower boiling point than salt the solvent particles evaporate from the mixture-in a condenser the water vapour condenses back to its liquids and pure liquid is collected in the beaker
49
describe the distillation of a mixture of ethanol and water?
the mixture of ethanol and water will be heated and since ethanol has a lower boiling point than water it will evaporate first leaving water in the mixture and its vapour will then travel through the condenser and condense back to its liquid state to be collected in a beaker
50
explain how the student ca separate the mixture to get pure samples of each substance(water substance y and x)
they can use fractional distillation to obtain water an x after this they can then use evaporation and crystallisation to obtain substance y (they cant let the mixture go dry as y decomposes if it gets to hot and water and x have different bp) they can the heat the mixture to remove the liquids and filter to separate y and dry it in a oven
51
what is chromatography?
a method of separation and analysis of a mixture of soluble chemical substances
52
what are the two phases in chromatography?
a mobile phase(solvent) a stationary phase(paper)
53
how does chromatography work?
as the solvent rises through the paper it dissolves the sample mixture which the separates the different chemical substances
54
what are the steps for chromatography?
1)get a small rectangular piece of paper and measure 1cm on the bottom and draw a line in pencil 2)use a pen and draw a dot on the line 3)fill the beaker with water to the tip of the paper 4)let strips develop for around 5 mins so that the mobile phase(solvent + dye) has moved over half way up
55
what is the equation for retention factor values?
distance from the base line to the spot/ distance from the base line to the solvent front
56
if it the same substance why has the rf changed?
a different solvent has been used the substance has a higher affinity for the new solvent(mobile phase) so it has moved further up the paper(stationary phase)
57
what is the stationary phase?
a thin layer of an inert substance supported on a flat unreactive surface
58
what is the advantages of thin layer chromatography over paper chromatography?
the mobile phase moves more quickly and evenly through the stationary phase there is also a greater separation of the components in the mixture so its easier to analyse
59
what is gas chromatography used for?
to detect banned substances in urine samples from athletes
60
what's the l

Chemistry (4 decks)

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