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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
Q

what happens to molecules with a high solubility and lower attraction to paper

A

they will travel further

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26
Q

how are components of a substance separated

A

they have different forces of attractions to the paper

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27
Q

what is formed between the mobile and stationary phases during chromotography

A

an equilibrium

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28
Q

which reaction to do to test for hydrogen

A

react zinc and sulphuric acid to form zinc sulphate and hydrogen

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29
Q

test for hydrogen

A

hold a lit splint in hydrogen

if the hydrogen is present it will make a squeaky pop

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30
Q

test for oxygen

A

a glowing splint relights

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31
Q

test for carbon dioxide

A

limewater (calcium hydroxide ) turns cloudy

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32
Q

test for chlorine

A

damp litmus paper is bleached white

33
Q

what is a cation

A

a metal ion

34
Q

process of a flame test

A

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
Q

what colour flame does a lithium ion have

A

crimson

36
Q

what colour flame does a sodium ion have

A

yellow

37
Q

what colour flame does a potassium ion have

A

lilac

38
Q

what colour flame does a calcium ion have

A

orange-red

39
Q

what colour flame does a copper ion have

A

green

40
Q

problem of flame test

A

doesn’t work with mixtures - some flame colours may hide others

41
Q

advantages of modern instrumental methods 3

A

expensive social training needed

results can only be interpreted by comparing with known substances

42
Q

what is flame emission spectroscopy used for

A

analyse samples for metal ions

43
Q

process of flame emission

A

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
Q

what happens when light emitted passes through a spectroscope

A

different wavelengths of light are detected to produce a line spectrum

45
Q

what is a substances line spectrum

A

the characteristics pattern of radiation absorbed and emitted

46
Q

why are no two ions line spectrums the same

A

it depends on the ions charge and electron arrangement msg different ions emit different wavelengths of light leading to different line spectrums

47
Q

what does the intensity of a spectrum indicate

A

the concentration of that ion in solution

48
Q

how can flame emission spectroscopy be used to identify different ions in mixtures

A

the spectrums for the different ions are created and then compared to the database

49
Q

how can the machine used for few indicate the concentration of an unknown

A

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
Q

how to test is a substance is a carbonate

A

it will fix and produce carbon dioxide

51
Q

equation and ionic equation for carbonate + acid

A

carbonate + acids -> carbon dioxide + water

52
Q

which two acids do you have to add to test for sulfate

A

barium chloride and hydrochloric acid

53
Q

what will form if sulfate ions are present when HCL and barium chloride are added

A

a white precipitate (barium sulfate)

54
Q

why must you add HCL before barium chloride when testing for sulphates

A

the hydrochloric acid gets rid of any carbonate ions, which would also form a precipitate with the barium chloride and confuse results

55
Q

ionic equation for testing for sulfates

A

ba ^2+ + SO4 ^2- -> BaS04

56
Q

what are the three halides we will be testing for

A

chlorine cl-
bromine br-
iodine I-

57
Q

process/test for halides

A

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
Q

why is nitric acid added when testing for halides

A

it dissolves compound and removes any carbonate ions as they would also form a precipitate and confuse results

59
Q

what colour precipitate will a chloride ion form and what is it

A

white

60
Q

what colour precipitate will a bromide ion form and what is it

A

cream

61
Q

what colour precipitate will a iodide ion form and what is it

A

yellow

62
Q

ionic equation for testing chloride ions

A

Ag+ + cl- -> AgCl

63
Q

ionic equation for testing for iodide

A

Ag+ + I - -> Agl

64
Q

ionic equation for testing for bromide ions

A

Ag + + Br- -> AgBr

65
Q

general ionic equation when testing for halides

A

aluminium, calcium and magnesium

66
Q

how to distinguish between calcium magnesium and aluminium ions

A

use a sodium hydroxide test
Aluminium precipitate will dissolve eventually
use a flame test

67
Q

what colour precipitate do calcium ions form in sodium hydroxide solution

A

white

68
Q

what colour precipitate do copper ions form in sodium hydroxide solution

A

blue

69
Q

what colour precipitate do iron ii ions form in sodium hydroxide solution n

A

green

70
Q

what colour precipitate do iron iii form in sodium hydroxide

A

brown

71
Q

what colour precipitate do aluminium ions form in sodium hydroxide solution

A

white but will eventually dissolve

72
Q

what colour precipitate do magnesium ions form in sodium hydroxide solution

A

white

73
Q

ionic equation for calcium ion + sodium hydroxide solution

A

cA2+ + 2OH- -> CaOH2

74
Q

ionic equation for copper ion +sodium hydroxide solution

A

Cu2+ +2OH- -> CuOH 2

75
Q

ionic equation for iron ii ion + sodium hydroxide solution

A

Fe2+ + 2OH- -> FeOH2

76
Q

ionic equation for iron iii ion + sodium hydroxide solution

A

Fe3+ + 3OH- ->FeOH3

77
Q

ionic equation for aluminium ion + sodium hydroxide

A

Al3+ +3OH- -> AlOH3

78
Q

ionic equation for magnesium ion + sodium hydroxide solution

A

Mg2+ +2OH- -> MgOH2

79
Q

why is a precipitate formed

A

it is insoluble

CHEMSITRY (13 decks)

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