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A-Level Chemistry > Extra stuff to know > Flashcards

Extra stuff to know Flashcards

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1
Q

Infrared radiation bonds/atoms

A

Absorb IR - makes them bend/stretch - heavier atoms vibrate more slowly
Stronger bonds vibrate faster

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2
Q

IR radiation atmosphere

A

Relatively unaffected by atmospheric gases - passes through atmosphere to earth’s surface where most is absorbed and some is re-emitted in the form of longer wavelength radiation ; greenhouse gases absorb THIS radiation and they re-emit as radiation which increases temp of atmosphere leading to global warming

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3
Q

Applications of IR

A

Many pollutants can be identified by their IR fingerprints
Breathalysers - more IR radiation absorbed from ethanol = more ethanol

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4
Q

UV

A

Ozone absorbs UV radiation from Sun’s rays on,y allowing a small amount to reach earth’s surface -

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5
Q

When measuring change in entropy

A

MOLES of gas matter

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6
Q

Reactions for fuel cells

A

Overall is the Enthalpy change that accompanies the formation of 1mol of H2O (l)

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7
Q

Acid fuel cell oxidation

A

H2 -> 2H+ + 2e-

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8
Q

Alkali fuel cell oxidation

A

H2 + 2OH- -> 2H2O + 2e-

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9
Q

Colour of copper iodide

A

White

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10
Q

Example of optical isomerism in transition

A

1-2 di amino ethane with 2 cl2 and Co central metal ion (+1 charge overall)

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11
Q

Cis platin

A

Pt central with 2cl and 2 nh3

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12
Q

Testing for bromine extra test

A

Use CONCENTRATED AMMONIA

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13
Q

Why do you use HNO3 first

A

Get ride of the possible white precipitate and any carbonate ions

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14
Q

Light brown precipitate

A

Mn(oh)2

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15
Q

Which hydrogen halide forms the strongest acid

A

HI - weakest bond Enthalpy thus dissociates to produce H+ ions when dissolves in water

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16
Q

Why are di carboxylic acids more soluble?

A

They contain 2 OH groups

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17
Q

When doing organic synthesis

A

Make sure to always add in HEAT

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18
Q

When asked to explain hydration Enthalpy

A

Always link it to attraction to water molecules

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19
Q

When asked to describe how anything except temperature affects K values (like Kc)

A

Just talk about how denominator and numerator changes to reverse the change and restore Kc

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20
Q

When talking about how Enthalpy change of solution changes

A

RATIO of energy produced to number of moles is the same

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21
Q

Why does Al have smaller ionisation energy than Mg

A

Mg has outer electron in 3s and Al has outer electron in 3p ; 3p is higher

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22
Q

Hexaaquacopper + KI

A

Copper iodide = white precipitate
I2 = brown solution

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23
Q

Cl2

A

Pale green

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24
Q

Bromine

A

Orange browney

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25
Q

Neutralisation

A

Exothermic

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26
Q

Why is water bath used

A

Easily controlled
And alcohol is flammable

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27
Q

Mno4 titration

A

Colourless to pink

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28
Q

Mno4- colour

A

Pink

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29
Q

Mn2+ colour

A

Colourless

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30
Q

Mno4- + Mn2+ ions

A

LOOK AT EQUATION AND HOW COLOUR CHANGES IN TITRATION

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31
Q

How to figure out degree of unsaturation via bromine molecules

A

Add in bromine dropwise - whichever one requires more drops = more unsaturated

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32
Q

If NH3 turns into NH4+ or a species forms a positive charge

A

LIKELY THEY HAVE ACTED AS A BASE - ACCEPTED A H+

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33
Q

When talking about H+ and OH- in half cell reactions

A

Equilibrium position what has reacted/been removed and then talk about E CELL VALUES

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34
Q

Enthalpy change (delta H)

A

Multiply by the number of moles (Stoichometry - number in front of species)

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35
Q

Explaining why delta G always positive/negative?

A

Break it down into what happens to delta H and t delta S

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36
Q

If increasing initial amount of a reactant in moles

A

The equilibrium amount of that reactant increases - shifts to the products and that increases too
BUT THE OTHER REACTANT DCEREASES - MORE OF IT HAS REACTED ; KC REMAINS THE SAME

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37
Q

When doing nitration of benzene

A

Concentrated HNO3 and CONCENTRATED H2SO4

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38
Q

Any aqueous (no solid) half cell

A

Include platinum electrode and like iodine aqueous and ions in solution

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39
Q

Zn + CuSO4

A

Blue to colourless - zinc displaces copper

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40
Q

When making standard solution

A

Add in LESS than 250cm^3 of water

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41
Q

When describing disproportionation

A

Use the word element not species

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42
Q

Redox reaction copper + iodine

A

2Cu2+ + 4I- -> 2CuI + I2

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43
Q

When explaining kp shifts

A

The last shift always = le chateliers

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44
Q

If you increase pressure of equilibrium

A

Increases pressure of the side of the equilibrium with the most amount of moles
Ratio of kp changes
THEN EQUILIBRIUM CHANGES WITH LE CHATELIERS ALWAYS THE FINAL SHIFT IS LE CHATELIERS

45
Q

Mg + water

A

Magnesium hydroxide + hydrogen

46
Q

Magnesium water

A

Magnesium + water -> Magnesium hydroxide + hydrogen

47
Q

Pre exponential factor A

A

Is responsible for increased frequency of collisions + correct orientation

48
Q

Graphite and graphene

A

3 bonding regions - 1 delocalised electron donated can conduct electricity
120 degrees - hexagonal layers

49
Q

Limitation of average bond Enthalpy

A

In gaseous state
AVERAGE calculated form bonds in different chemical environments

50
Q

Q=mcΔT

A

Dissipation of heat to surroundings
Incomplete combustion
Evaporation of methanol ALL LESS EXOTHERMIC
Non standard conditions

51
Q

As rate increases

A

So does k

52
Q

Mno4- to mn2+

A

Deep purple to colourless - read from top of meniscus

53
Q

Electrons in half cells

A

If mixed together (the solutions) they will flow uncontrollably and release energy

54
Q

Acid vs alkali fuel cell hydrogen

A

Continuously supplied with fuel and oxygen
No CO2 produced

55
Q

Acid more negative electrode

A

H2 -> 2H+ + 2e-

56
Q

Alkali more negative electrode

A

2OH- + H2 -> 2H2O + 2e-

57
Q

Why is a excess of a species used in a rates question?

A

To keep the equilibrium far to the other side -look at EQUILIBRIUM POSITION

58
Q

When talking about pH ratio

A

[HA]/[A-]

59
Q

Reaction with double the Stoichometry?

A

To figure out Kp just square root the Kp of the reaction with double the species

60
Q

At an equivalence point what is present?

A

Only salt and water

61
Q

End point

A

Point in a titration where the indicator changes colour

62
Q

What do we want with end point and equivalence point

A

We want both of them happening at the same time (as close together as possible) - end point should lie somewhere on that straight line (equivalence point is at the centre) - so we can observe sharp colour change

63
Q

What is the colour of an indicator at end point

A

It’s in between the acid and alkali colours so should be in the middle

64
Q

ph Probe

A

Remove from storage solution and rinse with distilled water

65
Q

Ph probe storage solution

A

Buffer solution KCl

66
Q

Phenolphthalein

A

Colourless in acid to red/purple in alkali

67
Q

Bromothymol blue

A

Yellow in acid and blue in alkali

68
Q

Methyl orange

A

Red in acid and yellow in alkali

69
Q

Strong base weak acid

A

Phenolphthalein

70
Q

Strong acid weak base

A

Methyl orange

71
Q

Standard hydrogen half cell

A

Hydrochloric acid 1mol dm^-3
Hydrogen gas at 100kPa
Inert platinum electrode

72
Q

Does salt bridge react with solution

A

NO

73
Q

Non rechargeable cells

A

Provide energy until all chemicals have reacted

74
Q

Rechargeable cells

A

Chemicals in the cell provide electrical energy - when recharging the reactions of the cells can be reversed

75
Q

Rechargeable cell example

A

Lithium ion batteries

76
Q

Drawbacks of lithium batteries

A

Toxic if ingested and rapid discharge of current can cause fire

77
Q

Disadvantage of fuel cells

A

Hydrogen is flammable with low bp ; hard and dangerous to store and transport

78
Q

Why might emf of a cell change over time

A

Concentration of ions change - reactants used up

79
Q

To keep emf constant

A

Ensure that reactants are supplied continuously

80
Q

[Cr(H2O]6]3+

A

Violet

81
Q

Mn2+ aqua

A

Pale pink

82
Q

Lime water + carbon dioxide

A

Forms calcium carbonate

83
Q

Enthalpy change of solution

A

Lattice Enthalpy + hydration Enthalpy together - they BOTH have an effect

84
Q

How to improve accuracy of titration

A

Take repeats
Reduce percentage error
3dp mass balance should be used

85
Q

Condensation

A

Exothermic

86
Q

What do photodegradable polymers break down into

A

Small particles of plastic that are biodegradable

87
Q

Formation of amines?

A

NH3 + haloalkane makes salt first
Then react salt with NaOH to make the amine

88
Q

TLC positioning

A

The plate is placed in a beaker of the solvent such that level of solvent is below the line

89
Q

Inert carrier gas example

A

Helium or neon

90
Q

Stationary phase of GLC

A

A liquid - solubility of sample in stationary phase is what determines it

91
Q

Why use a minimum amount of hot solvent?

A

To get a saturated solution - if too much solvent added then solution may be too dilute to form crystals ; more likely to dissolve any impurities if you use a lot of solvent

92
Q

Why to wet filter paper?

A

Keep it in place for the filtration

93
Q

When reducing nitrobenzene

A

Form NH3+ initially with Sn and HCl then NEUTRALISE WITH NAOH and this forms NH2

94
Q

Ch3COCl

A

Can polymerise without a catalyst

95
Q

Whenever describing heterocyclic fission

A

Both electrons from the COVALENT BOND are transferred

96
Q

Practical techniques organic

A

Dissolve in a minimum amount of hot solvent
Cool
Filter
Dry

97
Q

Longer chain

A

MORE SURFACE POINTS OF CONTACT

98
Q

Nucleophilic addition nitriles

A

NaCN + H2SO4

99
Q

Nucleophilic substitution

A

KCN (in ethanol)

100
Q

If it accepts a proton in a reaction

A

It is classed as a BASE

101
Q

With further substitution (radical substitution)

A

Going to need 2Cl2
Will create 2HCl (this is a di-substituted product)

102
Q

CFCs

A

Very stable - high bond enthalpies ; only attacked by UV in stratosphere

103
Q

Phenol + bromine

A

Decolourise and WHITE PPT

104
Q

C=C bond nature

A

LOCALISED

105
Q

Area under curve for GC

A

Relative concentration - actual concentration = use a calibration curve

106
Q

Primary/secondary/tertiary amines or amides

A

LOOK AT CARBON CHAINS ATTACHED TO NITROGEN

107
Q

Why can a given Kc expression be used to calculate Kc

A

Because units cancel - same number of moles each side?

108
Q

Why is Enthalpy change of solution the same?

A

Same energy released per mole of H2SO4

109
Q

Why do we use a solution in excess

A

Concentration of HCOOH remains constant?

A-Level Chemistry (28 decks)

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