F331 Flashcards
What is the mass number?
The number of protons and neutrons
How do you find relative atomic mass?
Average of the masses of the isotopes
What are alpha emissions?
A helium nucleus
What are beta emissions?
An electron
What is gamma emission?
Energy
What occurs in nuclear fusion?
Two light atomic nuclei fuse to form a single heavier nucleus
What is the use of radioisotopes?
Radiocarbon dating (ratio of carbon isotopes) in dead animals
Decay of rocks
Tracers
What is the Sun’s surface called?
The photosphere
What is the area outside the Suns photosphere called?
The chromosphere
What is the appearance of an absorption spectrum?
Black lines on coloured background
What appearance does an emission spectra have?
Coloured lines on a black background
How is the speed of sound related to wavelength?
C= wavelength*frequency
How do you get an atomic emission spectra?
Heat atoms in flame
Pass through slit
Pass through prism
How do you get an atomic absorption spectrum?
White light through heated atoms of element
Pass through slit
Pass through prism
What is the Lyman series?
The emission spectrum of hydrogen atoms in the UV region
What is Bohrs theory?
Atomic spectra caused by electrons changing shells
What is quantisation of energy?
Difference between sub-shells has a specific energy for an element
What is a dative covalent bond?
Both electrons from the same atom
What is electronegativity?
Measure of the ability of an atom in a molecule to attract electrons in a chemical bond to itself
What is metallic bonding?
Lattice of positive ions and pool of delocalised electrons
What is the shape and bond angle in a five atom compound like CH4?
Tetrahedral
109 degrees bonds
What shape is ammonia?
Pyramidal
What shape is water?
Bent
What is the shape and bond angles of BF3?
Planar triangular
120 degrees bond angles
What is the shape and bond angles when there are five groups of electrons around a centre atom?
Trigonal bipyramidal
120 or 90 degrees bond angles
What is the shape when six groups of electrons around the central atom?
Octahedral
What are the group 1 metals called?
Alkali metals
What are the group 2 elements called?
The alkaline earth metals
What do group 2 elements form when they react with water?
A hydroxide and hydrogen
What is formed when the group 2 oxides and hydroxides react with acids?
Salts and water
What is formed when heating group 2 elements carbonates?
Oxides and CO2
How does group 2 element solubilities change?
Increases going down for hydroxides
Decreases going down for carbonates
What is the atomic number?
The number of protons
What are feedstocks?
Starting materials
What is the equilibrium bond length?
The balance between attractive and repulsive forces
What is used to separate crude oil?
Fractional distillation
What are compound without a benzene ring called?
Aliphatic
What do alkanes oxidise to?
Carbon dioxide and water
What is formed in alkane isomerisation?
Branched alkanes
What are the conditions for alkane isomerisation?
Pt/Al2O3
150 C
What are the products of alkane isomerisation used for?
Improve octane numbers
What is the feedstock for alkane isomerisation?
C4 - C6 alkanes
What is the feedstock for alkane reforming?
Naphtha
What is the product in alkane reforming?
Cyclic alkanes
What are the conditions for alkane reforming?
Pt/Al2O3
500 C
Hydrogen recycled
What is the use of the alkane reforming products?
Improve octane number
What is the feedstock for alkane steam cracking?
Naphtha/kerosene
What are the products in alkane steam cracking?
Smaller alkanes and more molecules
What are the conditions for alkane steam cracking?
No catalyst
900C
Steam as a diluent
What is the use of the products of alkane steam cracking?
Manufacture polymers
What is the feedstock of alkane catalytic cracking?
Gas oil
What is the product of alkane catalytic cracking?
More molecules Fewer carbon atoms Some unsaturated Some branched Some cyclic
What are the conditions for alkane catalytic cracking?
Zeolite
500C
What are the products of alkane catalytic cracking used for?
Improving octane number
What is done with the fractional distillation residue?
Vacuum distilled
What does fuel contain more of in winter?
Volatile components
What is the octane number of a fuel?
Tendency to knock
What is knocking caused by?
Early auto-ignition
What is the difference between diesel and petrol?
Diesel has larger hydrocarbons
What decreases octane number?
Longer chain
Less branching
What does a low octane number represent?
High tendency to auto-ignite
What is chain isomerism?
Branching
What is position isomerism?
Differently positioned functional group
What is functional group isomerism?
Different functional groups
What is used to oxidise alcohols?
Acidified potassium dichromate (VI)
What is the colour change of dichromate in oxidation?
Orange to green
What are primary alcohols oxidised to?
Aldehydes then carboxylic acids
How is aldehyde extracted in alcohol oxidation?
Distillation
What are secondary alcohols oxidised to?
Ketones
What is the functional group of aldehydes?
-COH
What is the functional group of ketones?
Double bonded oxygen inside a chain
What are the conditions for alcohol dehydration?
Vapour of alcohol passed over hot catalyst of Al2O3
300C
What is formed in alcohol dehydration?
Alkene and water
What is the functional group of an ether?
R-O-R
What is a cetane number?
Higher number is greater ease of ignition under compression
What is entropy?
The amount of disorder in a system
What is evaporative emission?
Hydrocarbons lost as fumes from an engine
What is a photochemical reaction?
A reaction undergone when a molecule absorbs light energy
What is used to study pollutant effects?
Monitoring pollutants
Studying individual reactions in the lab
Modelling studies
Smog chamber simulations
How are catalysts used in cars?
Speed up reactions breaking down pollutants
What is a homogenous catalysis reaction?
All reactants and catalyst in the same state
What is a heterogeneous catalysis?
Reactants and catalyst in different states
How do heterogeneous catalysts work?
Reactants adsorbed on
New bonds form
How does catalyst poisoning occur?
Active sites blocked
What is the catalyst in catalytic converters?
150C
Platinum alloyed with rhodium
What are other fuel possibilities?
Lower volatility hydrocarbons
Ethanol
Biodiesel
Hydrogen