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lol Flashcards

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1
Q

Cell

A

A redox system which contains chemicals that react together to create electrical energy

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2
Q

Structure

A

Two metals in contact with an electrolyte

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3
Q

Size of PD depends on

A

Type of electrode
Concentration of electrolyte

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4
Q

Battery

A

2 or more cells connected in series

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5
Q

Non rechargeable batteries

A

Reaction at electrodes is irreversible
When all reactants run out, no voltage produced

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6
Q

Rechargeable batteries

A

Reaction at electrodes is reversible
Connect battery to pins and reverse current through it

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7
Q

Fuel cell

A

A cell which generates an electrical current as long as fuel and O2 are supplied

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8
Q

Negative electrode

A

H2 converted to H+ oxidation
H2 (g) -> 2H+ + 2e-

H+ travels through electrolyte
e- travels into electrical circuit generating a current

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9
Q

Positive electrode

A

H+ reacts w oxygen to form water reduction

4H+ (aq) + 4e- + O2 -> 2H2O

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10
Q

Overall reaction fuel cell

A

2 H2 (g) + O2 (g) -> 2 H2O (g)

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11
Q

Advantages of fuel cells

A

More accessible materials
Lower emissions
No toxic fumes
Fuel added makes it last longer

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12
Q

Disadvantages of fuel cells

A

Less accessible fuels
Less available infrastructure
H2 is explosive

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13
Q

Corrosion

A

The gradual destruction of materials by reaction with substances in the environment

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14
Q

Rust

A

The corrosion of iron
Forms hydrated iron oxides and hydroxide

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15
Q

Hydroxide ions half equation

A

4e- + O2 + 2H2O -> 4OH-

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16
Q

Iron ions half equation

A

Fe -> Fe 2+ + 2 e-

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17
Q

Iron further oxidised

A

Fe 2+ + O2 -> Fe 3+ + 2O2-

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18
Q

Iron hydroxides break down into oxides releasing water

A

Fe (OH) 2 -> FeO + H2O

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19
Q

Barrier method of preventing corrosion

A

Coating with paint or plastic
Oiling or greasing
Electroplating with less reactive metal

O2 and H2O cannot get to surface

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20
Q

Sacrificial protection

A

Blocks of more reactive metal corrode in place of less reactive metal

Galvanising adds a coat of zinc to stop O2 and H2O reaching surface

If scratched, Zn corrodes and not Fe

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21
Q

Low carbon steel

A

Easily shaped
Car bodies

0.1 to 0.3

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22
Q

High carbon steel

A

Strong but brittle
Construction
0.25 to 0.5

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23
Q

Stainless

A

Resists corrosion
Cutlery

Cu/Ni

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24
Q

Higher carbon content means

A

Harder for layers to slide, so higher CC = less malleable = less easy to slide = more brittle

25
Q

Why is Chromium used in steel (iron alloys)

A

More reactive, adding sacrificial protection, reducing corrosion

26
Q

Aluminum - why unpainted?

A

Forms a layer of unreactive AlO on surface, 2-3nm thick that doesn’t flake away

27
Q

What are alloys of Al used for

A

Low density

28
Q

Cu + Tin

A

Bronze

29
Q

Cu + Zinc

A

Brass

30
Q

Nitinol

A

Memory alloy reforms og shape when heated and cooled

31
Q

24 karats

A

100% gold

32
Q

12 karats

A

50% gold

33
Q

Why is gold alloyed

A

Hardness
Colour
Cheap

34
Q

Composites

A

Reinforcement
Matrix

Reinforcement provides strength
Matrix surrounds and holds reinforcement in place

35
Q

Ceramics

A

Shaping wet clay and heating in furnace
Forms cross links in a giant covalent structure

36
Q

Soda-lime glass

A

Sand limestone sodium carbonate

37
Q

Borosilicate

A

Sand and boron trioxide
Higher melting point

38
Q

Glass structure

A

Giant covalent

39
Q

Melting point in polymers

A

Strength of IM forces holding polymer chains together
Longer chain = stronger forces

Monomer used also affects strength of IM forces

40
Q

Polyethene reaction conditions

A

HDPE
LDPE

41
Q

Thermosoftening polymer

A

Melts
No cross links

42
Q

Haber process

A

Methane = Natural gas

Methane + steam -> Hydrogen + Carbon monoxide

Hydrogen + oxygen = water [removes o2 from air to leave N]

Nitrogen + Hydrogen -> Ammonia
N2 (g) + 3H2 (g) -> 2NH3 (g)

43
Q

Conditions for haber

A

450 degrees
200 atmospheres
Iron catalyst

44
Q

What does condensing ammonia do

A

Unused reactant gases separated from ammonia easily and recycled into reactor

Equilibrium position shifts to right as product is removed

45
Q

NPK fertiliser

A

Formulation and contains carefully measured salt quantities

46
Q

Nitrogen

A

Amino caids/proteins

47
Q

Phosphorous

A

DNA, root growth, flower production

48
Q

Potassium

A

Growth and crop yield

49
Q

Why is manure not used

A

Parasites

50
Q

Where does nitrogen come from in NPK

A

Haber

51
Q

Where does ammonium nitrate come from

A

Nitric acid + Ammonia -> Ammonium nitrate
HNO3 + NH3 -> NH4NO3

52
Q

Potassium salts

A

Mined

53
Q

Phosphorous

A

Extracted from phosphate rock

54
Q

Phosphate rock and H2SO4

A

Monocalcium phosphate
Calcium sulfate

55
Q

Phosphate rock and HNO3

A

Phosphoric acid
Calcium nitrate

56
Q

Phosphate rock and H3O4P

A

Calcium phosphate

57
Q

HDPE

A

High density
Higher melting point

58
Q

LDPE

A

Low density
Lower melting point

Z (old chemistry) (8 decks)

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