Developing Fuels Flashcards
What is the ideal gas equation?
pV =nRT
What are the standard conditions?
298K
1 atm
Is bond breaking exo or endo thermic?
Endo
Is making bonds endo or exo thermic?
Exo thermic
What is the mechanism of a heterogeneous catalyst?
Reactants adsorb to surface
Bonds are strained and broken
Bonds reform to make products
Product desorb away
What does a catalyst poison do?
Poisons adsorb to surface of catalyst more strongly than reactants so they don’t have a catalyst surface
What are the reaction conditions needed for cracking?
Hydrocarbon vapour over a heated catalyst
What does aliphatic mean?
There is no benzene ring
What does aromatic/ arene mean?
There is a benzene ring
What is a homologous series?
A group of compounds with the same functional group
What does incomplete combustion form?
Carbon monoxide, unburnt hydrocarbons and particulates
What is the test for saturation?
Bromine water
What catalyst is needed in the electrophillic addition of hydrogen to a Allene?
Nickel catalyst, heat and pressure
Or
Platinum catalyst with RTP
Define structural isomer,
Same molecular formula, different structural formula
What is a stereoisomers?
Same structural formula, different arrangement of atoms in space
Why are heterogeneous catalysts greener than homogeneous?
They are easier to separate from the product and recycle
what are the units for ideal gas equation?
p= pressure in pascals - Pa V= volume in m^2 n= number of moles R=gas constant T= temperature- K
what is significant about gases at the same temperature and pressure?
they take up the same volume per mole
what is the volume of 1 mole of gas at room temperature an pressure?
24dm^3
what is the enthalpy change of reaction?
the enthalpy change when the reaction occurs in molar quantities shown in the chemical equation
what is the enthalpy change of formation?
when one mole of product is formed from its elements in their standard states
what is the enthalpy change of combustion?
enthalpy change when one mole of substance is completely burned in oxygen
what is the enthalpy change of nuetralisation?
the enthalpy change when an acid and an alkali react together under standard conditions to form one mole of water
what is average bond enthalpy?
the energy needed to break one mole of bonds in the gas phase averaged out over many compounds
how can you measure enthalpy change
using calorimetry to measure temperature change of a reaction and then use q=mcΔT
what is hess’s law?
the total enthalpy change of a reaction is the same no matter which route is taken
what is the relationship between bond enthalpy and bond length?
the larger the bond enthalpy, the shorter the bond due to greater attraction between the molecules
what are the conditions needed for cracking?
passing hydrocarbon vapour over a heated solid catalyst
or at really high temperature and pressures
why is cracking done?
to make smaller hydrocarbons which are more useful
what is a functional group?
a specific group of atoms in a molecule that are responsible for the caracteristic chemical reactions of that molecule
what is a pi bond?
when 2 p orbitals overlap sideways, due to dumbell shape it forms below and above the molecular axis
what is a sigma bond?
overlapping of two orbitals
what does a double bond consist of?
a sigma and a pi bond
what shape are saturated hydrocarbons?
tetrahedral
what shape are unsaturated hyrdocarbons?
trigonal planar
what can cause structural isomerism?
different carbon skeleton (branching)
functional group in a different place
different functional group
what is the difference between E/Z and cis/trans?
E/Z must contain 1 hydrogen on each carbon in the c=c
what is formed under electrophillic adition with:
bromine
hydrogen bromide
water
dibromo alkane
bromoalkane
alcohol
what are the conditions needed for electrophillic addition with water?
concentrated sulfuric acid and water
or
steam withh phosphoric acid catalyst at high temperature and pressure
what is formed in complete combustion?
carbon dioxide and water
what is formed in incomplete combustion?
carbon monoxide and water
where do particulates come from and what are their implications?
from incomplete combustion- particles of liquid or carbon solid
causes respiratory promblems and cardiovascular problems
where do unburnt hydrocarbons come from and what are their implications?
from incomplete combustion
can react in sunlight to form ground level ozone which can damage lungs
where does carbon monoxide come from and what are their implications?
from incomplete combustion
it is toxic
where does carbon dioxide come from and what are their implications?
from combustion, it is a green house gas and causes global warming
where does NOx come from and what are their implications?
fromed in engines under high pressure and temperatures when oxygen and nitrogen in the air react
causes ground level ozone and photochemical smog
where does SOx come from and what does it cause?
from burning hydrocarbons with sulfur impurities
causes acid rain
why is enthalpy change calculated experimentally smaller than the theoretical value?
heat is lost to the surroundings
in complete combustion
evaporation of fuel from the wick
