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developing fuel Flashcards

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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
Q

bond making is

A

exothermic

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26
Q

% error calculation

A

% error = ( (theory - experiment) / theory) x 100

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27
Q

finding precision of apparatus

A

half the smallest division of apparatus (unless digital, then don’t halve)
if a difference in two readings, double the precision error

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28
Q

finding the % uncertainty

A

(precision / reading) x 100

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29
Q

hess cycle to find enthalpy change of formation

A

use enthalpy change of combustion
enthalpy change of formation = + enthalpy combustion of reactants - enthalpy combustion of products

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30
Q

hess cycle to find enthalpy change of reaction

A

use enthalpy change of formation
enthalpy change of reaction = - enthalpy change of reactants + enthalpy change of products

31
Q

catalyst purpose

A
  • increase rate of reaction but are chemically unchanged at the end of the reaction
  • provide an alternative pathway of lower activation energy
32
Q

homogeneous catalysis

A

reactants and catalyst in the same state

33
Q

heterogeneous catalysis

A

reactants and catalyst in different state

34
Q

mechanism of heterogeneous catalysis

A
  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
Q

catalyst poison definition

A

A substance that stops a catalyst from properly functioning

36
Q

cracking definition

A

the process of making one larger organic molecule into two or more smaller ones

37
Q

cracking conditions

A

very high temperatures and pressures

38
Q

catalytic cracking

A

alkane is heated and the vapour is passed over a hot zeolite catalyst
makes more branched products, better fuel

39
Q

thermal cracking

A

alkane vapour is mixed with steam and heated to a very high temperature
makes more short alkenes, makes straight chain fuels

40
Q

what are particulates

A

small particles of solids or liquids produced by volcanoes or burning fuel. can cause damage to animals and humans

41
Q

cause of photochemical smog

A

unburnt hydrocarbons from car engines

42
Q

what is CO + its dangers

A

carbon monoxide
from incomplete combustion
toxic gas
can cause photochemical smog

43
Q

dangers of CO2

A

contributes to the greenhouse effect

44
Q

dangers of nitrous oxides

A

produced through combustion of fuels in air
creates photochemical smog and acid rain

45
Q

dangers of sulfur oxides

A

produced by volcanoes and burning of fuels with sulfur impurities
lead to acid rain and are toxic

46
Q

dangers of acid rain

A

corrodes limestone and causes damage to life

47
Q

dangers of photochemical smog

A

reduces visibility and causes respiration problems

48
Q

methods of removing pollutants

A
  • catalytic converter
  • Sulfur oxides can be removed by reacting them with calcium oxide
49
Q

catalytic converter process

A

converts pollutants to safer molecules

50
Q

saturated hydrocarbon meaning

A

contains only single C-C bonds

51
Q

unsaturated hydrocarbon meaning

A

contains double C=C bond(s)

52
Q

benzene features

A
  • 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
Q

aromatic definition

A

A compound containing at least one ring of a planar flat molecule with delocalisation (such as benzene)

54
Q

aliphatic definition

A

compound with no rings

55
Q

homologous series definition

A

a group of compounds with the same general formulae but different molecular formulae

56
Q

general formula for alcohols

A

Cn H2n+1 OH

57
Q

general formula for alkanes

A

Cn H2n+2

58
Q

general formula for alkenes

A

Cn H2n

59
Q

general formula for cycloalkanes

A

Cn H2n

60
Q

complete combustion of a hydrocarbon

A

hydrocarbon + oxygen -> carbon dioxide + water

61
Q

incomplete combustion of a hydrocarbon

A

hydrocarbon + O2 -> H2O + CO + C

62
Q

polymers definition

A

long molecules made from smaller monomers

63
Q

copolymers definition

A

polymers consisting of multiple types of monomers

64
Q

addition polymers conditions

A

high pressure and catalyst

65
Q

addition reaction meaning

A

two or more molecules join, breaking a double bond to form a single product

66
Q

electrophile definition

A

electron pair acceptor (to form covalent bonds)
has partial positive charge

67
Q

testing for unsaturation

A

Add a few drops of low concentration bromine water to the sample and shake
if solution unsaturated, solution will turn colourless

68
Q

structural isomer definition

A

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
Q

E/Z isomerism criteria

A
  • C=C or ring (prevents rotation)
  • two different groups on each C in the C=C bond
70
Q

E isomer

A

opposite
hydrogen atoms are on opposite sides of double bond
aka trans isomers

71
Q

Z isomer

A

same
hydrogen atoms are on the same side of double bond
aka cis isomers

72
Q

features of biofuel

A
  • 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
Q

features of hydrogen as a potential fuel

A
  • created through electrolysis of water
  • combustion only produces only water
  • less energy dense than petrol
  • nitrous oxides still produced at high temperatures

chemistry (8 decks)

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