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O LEVEL GRIND > chemistry > Flashcards

chemistry Flashcards

1
Q

purpose of condenser jacket

A

increase contact time due to flow against gravity, then can condense water vapour for liquid to flow out

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2
Q

arrangement and movement
(solid)

A

very closely packed together in an orderly arrangement
vibrate in fixed positions

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3
Q

arrangement and movement
(liquid)

A

closely packed together but not in an orderly arrangement
slide and roll over each other and moving freely throughout the liquid

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4
Q

arrangement and movement
(gas)

A

far apart in random arrangement
moving freely at high speeds

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5
Q

straight line in a melting graph

A

temperature remains constant during change in state as heat energy is taken into overcoming the forces of attraction, holding the particles together instead of raising the temperature

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6
Q

straight line in a freezing graph

A

particles in the liquid give out energy and move slower
particles move closer together and eventually remain in their fixed positions

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7
Q

physical properties
(ionic compound)

A
  1. high mp and bp
  2. soluble in water but insoluble in organic solvents
  3. good conductor of electricity in the molten and aqueous state
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8
Q

high mp and bp
(ionic compound)

A

large amount of energy is needed to overcome the strong intermolecular forces between the oppositely charged ions

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9
Q

properties of covalent compound

A
  1. low mp and bp
  2. soluble in organic solvents but insoluble in water
  3. does not conduct electricity in any state
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10
Q

low mp and bp
(covalent compound)

A

little amount of energy is needed to overcome the weak intermolecular forces between the charged ions.

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11
Q

how are elements arranged ?

A

number of valence electron = group no.
number of electron shells = period no.

across the period, changes from metal to non-metals (metallic character decreases)

-> tendency to lose electrons decreases while tendency to gain electrons increases

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12
Q

physical properties
(group 1- alkali metals)

A
  1. low mp and bp
  2. low density
  3. soft and easily cut with a knife
  4. good conductor of electricity and heat
  5. shiny and silvery in colour
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13
Q

trend of alkali metal

A

down the group ,
mp and bp decreases
reactivity increases

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14
Q

physical properties
(group 7- halogens)

A
  1. exists as diatomic molecules
    -> two atoms chemically combined together
  2. coloured non-metals
  3. low mp and bp
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15
Q

trend of halogens

A

down the group,
mp and bp increases
reactivity decreases
colour intensity increases

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16
Q

colour of each halogen

A

F2 - pale yellow gas
Cl2 - yellow gas
Br2 - red-brown liquid
I2 - black solid
At2 - black solid

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17
Q

physical properties
(group 0 - noble gases)

A
  1. low mp and bp
  2. exists as monoatomic gases
  3. colourless non-metals
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18
Q

physical properties of metals

A
  1. high mp and bp
    -> a lot of energy is required to overcome the strong electrostatic forces of attraction between positively charged metal ions and negatively charged electrons
  2. good conductor of electricity and heat
    -> presence of free and mobile delocalised electrons to carry electrical charges
  3. malleable and ductile
    -> atoms are arranged in an orderly manner hence the layers of atoms can slide over each other easily when a force is applied
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19
Q

example of an alloy

A

brass
-> copper and zinc

steel
-> iron and carbon

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20
Q

alloys are harder and stronger than pure metals

A

presence of different sized atoms disrupt the orderly arrangement of atoms , making it difficult for the layers of atoms to slide over each other easily when a force is applied

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21
Q

why is aluminium unreactive ?

A

aluminium reacts with oxygen in the air to form a layer of aluminium oxide which prevents aluminium from further reaction .

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22
Q

raw materials of extraction

A

haematite , Fe2O3
coke , C
limestone , CaCO3

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23
Q

why are recycling metals important ?

A
  • finite resources which we must conserve
  • requires less energy than extracting metals , saving energy
24
Q

precipitation

A

prepare an insoluble salt ,
2 soluble reagents

25
Q

titration

A

preparing “SPA” salts,
2 soluble reagent
-> acid
-> alkali

26
Q

reaction of acids

A

prepare non-SPA soluble salts,
1 soluble reagent
(acid)
1 insoluble reagent
(metal/ base/ carbonate )

27
Q

factors affecting speed of reaction

A
  1. concentration
  2. pressure
  3. particle size
  4. temperature
28
Q

carbon monoxide, CO

A

source: incomplete combustion of carbon-containing fuels

harmful effect: combines with haemoglobin in red blood cell and prevents oxygen supply to all parts of the body

29
Q

surfer dioxide , SO2

A

source: burning of fossil fuels in factories, volcanic eruptions

harmful effect: react with water vapour and oxygen in the air to form acid rain which damages limestone building

30
Q

oxides of nitrogen , NOx

A

source: lightning activity

harmful effect: react with water vapour and oxygen in the air to form acid rain which damages limestone building

31
Q

differences between boiling and evaporation

A

boiling:
bubbles observed
takes places throughout the liquid
fast process

evaporation:
no bubbles observed
takes paces on the studs elf the liquid
slow process

32
Q

definition of isotopes

A

atoms of the same element with the same number of protons but different number of neutrons

33
Q

QA ANALYSIS

A

anions:
- add silver ,, chloride present
- add barium ,, sulfate present
- add aluminium ,, nitrate present
- add acid which give out co2 ,, carbonate present

34
Q

Testing for unsaturated compounds

A

TEST : add substance to aqueous bromine
OBSERVATIONS : red-brown aqueous bromine turns colourless if substance is an alkene
OBSERVATIONS : red-brown aqueous broke remains of substance is an alkane

35
Q

pollution problems caused by disposal of poly(ethene)

A

1) plastics are non-biodegradable hence it fills up landfills, causing air pollutions

2) plastics produces toxic fumes when burnt , causing air pollution

36
Q

oxides

A

acidic oxides
- oxides of non-metal
- react with base

basic oxides
- oxides of metal
- react with acids

amphoteric oxides
- react with both acidic or base
- ZnO, Al2O3 , PbO

neutral oxide
- do not react
- NO, CO, H2O

37
Q

define exothermic

A

a change which transfers energy to the surroundings
- temp rise

examples are
condensation , metal displacement reaction

38
Q

define endothermic

A

is a change that takes in energy from the surroundings
- temp fall

examples
ammonium chloride

39
Q

format to explain SOR

A
  1. factor
  2. reason
  3. frequency of effective collisions
  4. S.O.R

examples
- concentration increases
- more particles per unit volume
- higher frequency of effective collisions b/w reacting particles (specify)
- s.o.r increases

40
Q

oxidation and reduction

A

oxidation
+ S
- H
+ O
- E

reduction
- S
+ H
- O
+ E

41
Q

rules to work out O.S

A

1) elements have O.S of 0
2) O.S of a simple ion is the charge on the ion
3) O.S of hydrogen +1 , O2 -2 , grp 1 +1 , grp 2 +2
4) O.S of e- in a compound add up to zero
5) sum of O.S of the e- in an ion = charge in the ion

42
Q

uses for petroleum gas

A

fuel for cooking

43
Q

uses for petrol

A

fuel for motor cars

44
Q

uses for naphtha

A

making petrochemicals

45
Q

uses for kerosene

A

fuel for aircraft, heating and cooking

46
Q

uses for diesel

A

fuel for buses, taxis and lorries

47
Q

uses for lubricating oil

A

lubricants for waves

48
Q

uses for bitumen

A

surfacing roads

49
Q

homologous series of alkanes

A

1) same general formula , CnH2n+2
2) similar chemical properties as they have same functional group
3) show a gradation in physical properties
4) each member differs from the next by -CH2- group of atoms

50
Q

physical properties of alkanes and alkenes

A

as no. of carbon atoms increase,
mp & bp increases
density increases
viscosity increases ( ability to flow)
flammability decreases (ability to catch fire)
solubility (insoluble in water)

51
Q

why do mp & bp increases as no. of carbon atoms increases ?

A

molecular size increases
surface area increases
intermolecular forces of attraction increase
energy required to overcome intermolecular forces of attraction increase

52
Q

chemical properties of alkanes

A

1) combustion
- complete combustion (gives out CO2 + H2O)
2) substitution with chlorine
- ultraviolet light is needed

53
Q

homologous series of alkene

A

1) same general formula , CnH2n
2) similar chemical properties as they have same functional group
3) show a gradation in physical properties
4) each member differs from the next by -CH2- group of atoms

54
Q

cracking of alkanes molecules

A

chemical reaction which breaks up large and long-chain alkane molecules into smaller and more useful hydrocarbons molecules and/or hydrogen

55
Q

conditions for cracking to take place

A
  • high temp of 600degree
  • finely divided aluminium oxide catalyst
56
Q

chemical properties of alkenes

A

1) combustion
- complete combustion (gives out CO2 + H2O)
2) bromination
- dibromoethane
3) hydrogenation
- presence of nickel catalyst at 200degree

O LEVEL GRIND (4 decks)

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