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CHEMSITRY > CHAPTER 12 > Flashcards

CHAPTER 12 Flashcards

1
Q

what is a pure substance

A

something made from just one substance

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2
Q

what can a put substance be

A

an element or a compound

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3
Q

what are the fixed points of an element or compound

A

its melting and boiling points

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4
Q

test for water

A

turns white, anhydrous copper sulphate blue

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5
Q

test for pure water

A

its melting point is exactly 0 degrees and its boiling point is exactly 100

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6
Q

how can the fixed point of substance be used to identify it

A

pure substances have specific temperatures at which they boil/melt and these can then be checked in a data base

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7
Q

what will impurities do to the melting point of a substance

A

it will lower it

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8
Q

what will impurities do to the melting range of a substance

A

it will increase it

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9
Q

what will impurities do to the boiling point of a substance

A

it will increase it

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10
Q

how to test a substance’s purity

A

measure its melting and boiling points

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11
Q

what is a formulation

A

a mixture with a specific purpose

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12
Q

examples of formulations 4

A

paint
tablets
cosmetics
fertilisers

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13
Q

main components of a tablet 4

A

active drug
smooth coatings
colourants
sweeteners

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14
Q

why is the formulation of a tablet so important

A

it must have a long enough shelf life, be consumed,able and deliver the drug to the right part of the body

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15
Q

main components and functions of these in paints

A

pigment for color
solvent - alters viscosity for easy painting
binder- forms a protective film when paint dries

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16
Q

what is chromatography

A

an analytical method used to separate substances in a ,mixture

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17
Q

what are the two phases in chromotography

A

mobile phase

stationary phase

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18
Q

what is the mobile phase

A

where the molecules can move. it is a liquid and is what carries molecules up the stationary phase

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19
Q

what is the stationary phase

A

where the molecules can’t move and are carried by solvent

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20
Q

what is the rf value

A

a ratio of the distance travelled by the solute and the solvent

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21
Q

how to calculate rf

A

distance travelled by substance / distance travelled by solvent

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22
Q

why is the rf value useful

A

if two rf values match the substance may be present, it is an easy means of comparison

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23
Q

what does a single spot on a chromatogram show

A

a pure substance

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24
Q

what does the amount of time molecules spend in each phase depend on

A

how soluble they are in the solvent how attracted they are to paper

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25
what happens to molecules with a high solubility and lower attraction to paper
they will travel further
26
how are components of a substance separated
they have different forces of attractions to the paper
27
what is formed between the mobile and stationary phases during chromotography
an equilibrium
28
which reaction to do to test for hydrogen
react zinc and sulphuric acid to form zinc sulphate and hydrogen
29
test for hydrogen
hold a lit splint in hydrogen | if the hydrogen is present it will make a squeaky pop
30
test for oxygen
a glowing splint relights
31
test for carbon dioxide
limewater (calcium hydroxide ) turns cloudy
32
test for chlorine
damp litmus paper is bleached white
33
what is a cation
a metal ion
34
process of a flame test
a nichrome wire is dipped in hydrochloric acid then heated to clean it redid wire in acid then into unknown substance hold loop in blue flame record colour of flame
35
what colour flame does a lithium ion have
crimson
36
what colour flame does a sodium ion have
yellow
37
what colour flame does a potassium ion have
lilac
38
what colour flame does a calcium ion have
orange-red
39
what colour flame does a copper ion have
green
40
problem of flame test
doesn't work with mixtures - some flame colours may hide others
41
advantages of modern instrumental methods 3
expensive social training needed | results can only be interpreted by comparing with known substances
42
what is flame emission spectroscopy used for
analyse samples for metal ions
43
process of flame emission
sample placed in a flame ions heat up electrons become excited and jump into higher shells when they drop back they emit energy as light passes through a spectroscope
44
what happens when light emitted passes through a spectroscope
different wavelengths of light are detected to produce a line spectrum
45
what is a substances line spectrum
the characteristics pattern of radiation absorbed and emitted
46
why are no two ions line spectrums the same
it depends on the ions charge and electron arrangement msg different ions emit different wavelengths of light leading to different line spectrums
47
what does the intensity of a spectrum indicate
the concentration of that ion in solution
48
how can flame emission spectroscopy be used to identify different ions in mixtures
the spectrums for the different ions are created and then compared to the database
49
how can the machine used for few indicate the concentration of an unknown
the spectrometer measures the intensity of light with a specific wavelength that is known to be a characteristic of an ion the machine is calibrated using solutions of the metal ion of known concentrations it can then give a value for the unknown concentration
50
how to test is a substance is a carbonate
it will fix and produce carbon dioxide
51
equation and ionic equation for carbonate + acid
carbonate + acids -> carbon dioxide + water
52
which two acids do you have to add to test for sulfate
barium chloride and hydrochloric acid
53
what will form if sulfate ions are present when HCL and barium chloride are added
a white precipitate (barium sulfate)
54
why must you add HCL before barium chloride when testing for sulphates
the hydrochloric acid gets rid of any carbonate ions, which would also form a precipitate with the barium chloride and confuse results
55
ionic equation for testing for sulfates
ba ^2+ + SO4 ^2- -> BaS04
56
what are the three halides we will be testing for
chlorine cl- bromine br- iodine I-
57
process/test for halides
add few drops of dilute nitric acid to the unknown then add a few drops of silver nitrate solution if a precipitate forms, halide ions are present
58
why is nitric acid added when testing for halides
it dissolves compound and removes any carbonate ions as they would also form a precipitate and confuse results
59
what colour precipitate will a chloride ion form and what is it
white
60
what colour precipitate will a bromide ion form and what is it
cream
61
what colour precipitate will a iodide ion form and what is it
yellow
62
ionic equation for testing chloride ions
Ag+ + cl- -> AgCl
63
ionic equation for testing for iodide
Ag+ + I - -> Agl
64
ionic equation for testing for bromide ions
Ag + + Br- -> AgBr
65
general ionic equation when testing for halides
aluminium, calcium and magnesium
66
how to distinguish between calcium magnesium and aluminium ions
use a sodium hydroxide test Aluminium precipitate will dissolve eventually use a flame test
67
what colour precipitate do calcium ions form in sodium hydroxide solution
white
68
what colour precipitate do copper ions form in sodium hydroxide solution
blue
69
what colour precipitate do iron ii ions form in sodium hydroxide solution n
green
70
what colour precipitate do iron iii form in sodium hydroxide
brown
71
what colour precipitate do aluminium ions form in sodium hydroxide solution
white but will eventually dissolve
72
what colour precipitate do magnesium ions form in sodium hydroxide solution
white
73
ionic equation for calcium ion + sodium hydroxide solution
cA2+ + 2OH- -> CaOH2
74
ionic equation for copper ion +sodium hydroxide solution
Cu2+ +2OH- -> CuOH 2
75
ionic equation for iron ii ion + sodium hydroxide solution
Fe2+ + 2OH- -> FeOH2
76
ionic equation for iron iii ion + sodium hydroxide solution
Fe3+ + 3OH- ->FeOH3
77
ionic equation for aluminium ion + sodium hydroxide
Al3+ +3OH- -> AlOH3
78
ionic equation for magnesium ion + sodium hydroxide solution
Mg2+ +2OH- -> MgOH2
79
why is a precipitate formed
it is insoluble

CHEMSITRY (13 decks)

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