Organic Chemistry Flashcards
What type of resource is crude oil?
Finite
Where is crude oil found?
In rocks
How was crude oil formed?
Remains of an ancient biomass consisting mainly of plankton that was buried in mud
What is crude oil?
Mixture of hydrocarbons
What is a hydrocarbon?
A substance made up of only hydrogen and carbon elements
What type of hydrocarbons are found in crude oil?
Alkenes
What is the general formula of an alkane?
CnH2n+2
What is a homologous series?
A series of organic compounds that have the same general formula e.g. alkanes CnH2n+2
What are the first four alkanes?
Methane,ethane,propane,butane
How can alkanes be represented?
Molecular formula that shows the number of atoms of each element e.g. C2H6,displayed formula (stick drawing)
How is crude oil separate into its fractions?
Fractional distillation
What two processes are involved in fractional distillation?
Evaporation and condensation
What is a fraction?
groups of hydrocarbons of similar chain lengths
What are fractions used to produce?
Fuels and feedstock for the petrochemical industry
Name some fractions produced from crude oil
Pertrol,diesel oil,kerosene,heavy fuel oil,liquified petroleum gases (lpg)
What products are produced from the petrochemical industry? (4)
Solvents,lubricants,polymers,detergents
How is crude oil separated? (Havebfchprcdbphsmlblmhbpcb)
Crude oil is heated to become a vapour,it enters the bottom of the fractionating column (hottest part as it cools higher up),vapour rises and condenses at different boiling points,different fractions collected at different levels,hydrocarbons have the smallest molecules with the lowest boiling points so they are collected at the top,large molecules have higher boiling points are collected at the bottom
Where are the largest molecules found ?
Bottom of the fractionating column (highest boiling point)
Where are the smallest molecules found?
Top of the fractionating column (lowest boiling point)
What are the trends in the properties of alkanes?
As molecular size increases so does boiling points and viscosity but flammability decreases
Why do large molecules have the highest boiling points?
There are more intermolecular forces between molecules therefore more energy is required to overcome
What is released during combustion of a hydrocarbon?
Energy
What are the two types of combustion?
Complete and incomplete
Describe the difference between the two types of combustions?
Complete combustion = large supply of oxygen Incomplete combustion = limited supply of oxygen
What happens to the carbon and hydrogen when a hydrocarbon is burnt?
They are oxidised (both gain oxygen to become CO2 and H20)
What is produced during the complete combustion a hydrocarbon?
Carbon dioxide and water
Write a word equation for the complete combustion of propane
Propane + oxygen —> carbon dioxide and water
Write a balanced symbol equation for the combustion of propane (Tip: balance C first then H)
C3H8 + 5O2 —> 3O2 + 4H2O
How are hydrocarbons broken down into smaller more useful molecules?
Cracking
Why are hydrocarbons cracked?
To meet demand for high demand products e.g. fuels
What are two methods of cracking?
Catalytic and steam
What are the conditions for catalytic cracking?
Temperatures of 550C,zeolite catalyst (made of aluminium oxide and silicon oxide)
What are the conditions for steam cracking?
Higher temperature than catalytic cracking and no catalyst
What type of hydrocarbon is formed during cracking?
Alkenes
Which type of hydrocarbon is more reactive?
Alkenes
What is the test for an alkene?
Bromine water (orange) changes to colourless
What is produced from Alkenes?
Polymers and starting materials for the production of many other chemicals
Balanced equation showing cracking
Sum of reactants = product
