OCR F331 Developing Fuels

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Chemistry for Life: Developing Fuels
Formulae, Equations and Amount of Substance
(a) use the concept of amount of substance to perform calculations involving:
Volumes of Gases Number of Moles = Volume in dm3
24
e.g. Calculate the number of molecules in 18dm3 of carbon dioxide at r.t.p.
Number of Moles = 18 = 0.75 moles of CO 2 molecules
24
Number of Molecules = 0.75 x 6.02x1023 = 4.52x1023 molecules of CO 2
Balanced Chemical
Equations
Enthalpy Changes (H) e.g. Calculate the overall enthalpy change for this reaction:
N 2 + 3H
2 2NH 3
Bonds Broken: 1 x N N = 1 x 945 = 945kJmol1
3 x HH = 3 x 436 = 1308kJmol1
= 2253kJmol1
Bonds Formed: 6 x NH = 6 x 391 = 2348kJmol1
= 2346kJmol1
Enthalpy Change of Reaction = Energy to Break Bonds Energy to Make Bonds
= 2253 2346 = 93kJmol1
Energetics
(b) explain and use the terms:
Exothermic When energy is released/ given out gives a negative enthalpy
e.g. bond making, combustion, oxidation
Endothermic When energy is gained/ absorbed gives a positive enthalpy
e.g. bond breaking, thermal decomposition, photosynthesis
Standard State The state at which an element is in at:
a specified temperature (
25o C or 298K)
a standard pressure of 1 atmosphere
a standard concentration of 1 mole
Standard Enthalpy Change of Reaction (Hr)
The enthalpy change when molar quantities of reactants as
stated in the equation react under stated conditions
Standard Enthalpy Change of Combustion The enthalpy change that occurs when one mole of a substance
( Hc) is burned completely in oxygen under standard conditions
Standard Enthalpy Change of Formation ( Hf)
The enthalpy change when one mole of a compound is formed
from its elements in their standard states under standard
conditions

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Chemistry for Life: Developing Fuels
(c) describe and design simple experiments to measure the energy transferred when reactions occur in solution
or when flammable liquids burn; explain the limitations of such practical procedures and the uncertainties of
measurements involved
In calorimetry you can find how much heat is given out by a reaction by measuring the temperature change of
some water.…read more

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Chemistry for Life: Developing Fuels
3.Work out the heat produced by 1 mole of fuel = 26.125
= 1306kJmol1
0.…read more

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Chemistry for Life: Developing Fuels
(g) use the term entropy in a qualitative manner, interpreting it as a measure of the number of ways that
molecules can be arranged
Entropy is a measure of the amount of disorder in a molecule. It measures the number of different ways the
particles can be arranged .
Gases have higher entropies than liquids, which have higher entropies than solids.
Larger molecules or atoms have higher entropies than smaller molecules or atoms.…read more

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Chemistry for Life: Developing Fuels
(k) describe the use of catalysts (including zeolites) in isomerisation, reforming and cracking processes and in
the control of exhaust emissions
Isomerisatio Conditions:
n Catalyst: Platinum on aluminium oxide (big surface area and aluminium oxide is cheap)
o
150 C
Zeolite catalyst (a mineral with minute tunnels and cavities) used as a molecular sieve
to separate the straight chain and branched
Reforming Conditions:
Catalyst: Platinum on aluminium oxide (big surface area and aluminium oxide is cheap)
o
500 C
Hydrogen…read more

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Chemistry for Life: Developing Fuels
Acid rain is formed by burning fossil fuels that contain sulfur .…read more

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Chemistry for Life: Developing Fuels
Alcohols
C
nH
2n+1OH
Esters oxygen
atom in
between carbon
chain
(o) explain the terms:
Aliphatic Compounds that do not contain a benzene ring
Aromatic Compounds that do contain a benzene ring
Saturated Compounds that contain only single bonds between carbon atoms no
double bonds
Unsaturated Compounds that contain at least one double or triple bonds between
carbon atoms
(p) use systematic nomenclature to name, and interpret the names of, alkanes and alcohols
Rule 1: Count the carbon atoms in…read more

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Chemistry for Life: Developing Fuels
Rule 3: Identify the position of each substituent by a number. The numbering is done from the end of the
carbon that gives the lowest number for the substituent group.…read more

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Chemistry for Life: Developing Fuels
When a carbon atom makes four single bonds, the angle between any two of the covalent bonds is
109.5O . This
forms a tetrahedral shape.
When there's a double bond and two single bonds, the bond angles are
120o and is said to be trigonal planar. The
outside atoms around the central carbon make a equilateral triangle.…read more

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