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developing fuel Flashcards

(73 cards)

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1
Q

ideal gas equation

A

pressure x volume = moles x ideal gas constant x temperature

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2
Q

units for ideal gas equation

A

pressure - pascals
volume - meters cubed
temperature - kelvin

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3
Q

conversion to pascals

A

atm x 1.01 x10^5 = Pa
kPa x10^3 = Pa

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4
Q

conversion to meters cubed

A

cm^3 x10^-6 = m^3
dm^3 x10^-3 = m^3

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5
Q

conversion to Kelvin

A

C + 273 = K

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6
Q

type of bonds in a single C-C bond

A

a sigma bond
electrons are arranged in an area of increased electron density between the carbon atoms
the orbitals for the two bonding electrons overlap in a straight line

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7
Q

type of bonds in a C=C double bond

A

a pi and a sigma bond
pi bond has two areas of negative charge and high electron density, above and below the σ bond
pi bond is weaker than a sigma bond

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8
Q

enthalpy meaning

A

The energy change from start to finish in a chemical reaction is its enthalpy

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9
Q

exothermic reaction meaning

A

energy released from system to the surroundings, increase in surroundings temperature, negative enthalpy

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10
Q

endothermic reaction meaning

A

energy absorbed from surroundings to system, decrease in surroundings temperature, positive value

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11
Q

standard conditions

A

1 atm pressure
298 K temperature
1.0 moldm-3 concentrations

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12
Q

units of enthalpy

A

kJmol-1

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13
Q

change in enthalpy symbol

A

delta H

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14
Q

enthalpy change of reaction

A

delta r H
the enthalpy change that accompanies a reaction under standard conditions

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15
Q

enthalpy change of combustion

A

delta c H
the enthalpy change when one mole of a substance is burnt completely in excess oxygen under standard conditions (in standard states)

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16
Q

enthalpy change of formation

A

delta f H
the enthalpy change when one mole of a compound in its standard state is formed from its constituent elements in their standard states under standard conditions

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17
Q

enthalpy change of neutralisation

A

delta neut H
the enthalpy change when one mole of H+ ions reacts with one mole of OH- ions to form one mole of water under standard conditions

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18
Q

calculating enthalpy change of combustion through experiment

A

method : calorimetry
1. measure 100 cm3 water into metal calorimeter
2. measure initial temperature of water
3. weigh + record initial mass of spirit burner
4. set up apparatus as shown, heat water, while stirring, until temperature stops changing
5. extinguish fuel by placing lid and reweigh spirit burner
6. record max temperature of water

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19
Q

calculating enthalpy change of combustion experiment calculations

A

a. q = m c deltaT
q (J) = mass of water x s.h.c x change in temp
b. n(fuel) = mass / Mr
c. enthalpy change of combustion = -q (kJ) / mol fuel
units = kJmol-1

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20
Q

enthalpy profile of exothermic reaction

A

reactants above products

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21
Q

enthalpy profile of endothermic reaction

A

products above reactants

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22
Q

bond enthalpy definition

A

the energy required to break one mole of the stated bond in a gaseous state, under standard conditions

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23
Q

bond enthalpy equation

A

bond enthalpy = bonds broken - bonds made

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24
Q

bond breaking is

A

endothermic

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25
bond making is
exothermic
26
% error calculation
% error = ( (theory - experiment) / theory) x 100
27
finding precision of apparatus
half the smallest division of apparatus (unless digital, then don't halve) if a difference in two readings, double the precision error
28
finding the % uncertainty
(precision / reading) x 100
29
hess cycle to find enthalpy change of formation
use enthalpy change of combustion enthalpy change of formation = + enthalpy combustion of reactants - enthalpy combustion of products
30
hess cycle to find enthalpy change of reaction
use enthalpy change of formation enthalpy change of reaction = - enthalpy change of reactants + enthalpy change of products
31
catalyst purpose
- increase rate of reaction but are chemically unchanged at the end of the reaction - provide an alternative pathway of lower activation energy
32
homogeneous catalysis
reactants and catalyst in the same state
33
heterogeneous catalysis
reactants and catalyst in different state
34
mechanism of heterogeneous catalysis
1. reactants diffuse towards catalyst surface 2. reactants adsorb onto catalyst surface (weakens bonds and lowers activation energy) 3. weaker bonds in the molecule break 4. new bonds in molecules form (new products form on catalyst surface) 5. products desorb from the catalyst surface
35
catalyst poison definition
A substance that stops a catalyst from properly functioning
36
cracking definition
the process of making one larger organic molecule into two or more smaller ones
37
cracking conditions
very high temperatures and pressures
38
catalytic cracking
alkane is heated and the vapour is passed over a hot zeolite catalyst makes more branched products, better fuel
39
thermal cracking
alkane vapour is mixed with steam and heated to a very high temperature makes more short alkenes, makes straight chain fuels
40
what are particulates
small particles of solids or liquids produced by volcanoes or burning fuel. can cause damage to animals and humans
41
cause of photochemical smog
unburnt hydrocarbons from car engines
42
what is CO + its dangers
carbon monoxide from incomplete combustion toxic gas can cause photochemical smog
43
dangers of CO2
contributes to the greenhouse effect
44
dangers of nitrous oxides
produced through combustion of fuels in air creates photochemical smog and acid rain
45
dangers of sulfur oxides
produced by volcanoes and burning of fuels with sulfur impurities lead to acid rain and are toxic
46
dangers of acid rain
corrodes limestone and causes damage to life
47
dangers of photochemical smog
reduces visibility and causes respiration problems
48
methods of removing pollutants
- catalytic converter - Sulfur oxides can be removed by reacting them with calcium oxide
49
catalytic converter process
converts pollutants to safer molecules
50
saturated hydrocarbon meaning
contains only single C-C bonds
51
unsaturated hydrocarbon meaning
contains double C=C bond(s)
52
benzene features
- a hydrocarbon (C6H6) - in a closed ring shape - It has three double bonds, but the p electrons are delocalised around the whole ring so it reacts slightly differently to other hydrocarbons with double bonds -
53
aromatic definition
A compound containing at least one ring of a planar flat molecule with delocalisation (such as benzene)
54
aliphatic definition
compound with no rings
55
homologous series definition
a group of compounds with the same general formulae but different molecular formulae
56
general formula for alcohols
Cn H2n+1 OH
57
general formula for alkanes
Cn H2n+2
58
general formula for alkenes
Cn H2n
59
general formula for cycloalkanes
Cn H2n
60
complete combustion of a hydrocarbon
hydrocarbon + oxygen -> carbon dioxide + water
61
incomplete combustion of a hydrocarbon
hydrocarbon + O2 -> H2O + CO + C
62
polymers definition
long molecules made from smaller monomers
63
copolymers definition
polymers consisting of multiple types of monomers
64
addition polymers conditions
high pressure and catalyst
65
addition reaction meaning
two or more molecules join, breaking a double bond to form a single product
66
electrophile definition
electron pair acceptor (to form covalent bonds) has partial positive charge
67
testing for unsaturation
Add a few drops of low concentration bromine water to the sample and shake if solution unsaturated, solution will turn colourless
68
structural isomer definition
the same molecular formula as another isomer but a different structural formula (so it has the same number of atoms, but in a different arrangement)
69
E/Z isomerism criteria
- C=C or ring (prevents rotation) - two different groups on each C in the C=C bond
70
E isomer
opposite hydrogen atoms are on opposite sides of double bond aka trans isomers
71
Z isomer
same hydrogen atoms are on the same side of double bond aka cis isomers
72
features of biofuel
- produced from plant / animal materials - burning them still releases CO2 - if the plants/trees used to produce them are replanted, the new ones 'reabsorb' this CO2 with photosynthesis
73
features of hydrogen as a potential fuel
- created through electrolysis of water - combustion only produces only water - less energy dense than petrol - nitrous oxides still produced at high temperatures

chemistry (12 decks)

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