Organic Chemistry Flashcards
What is crude oil?
A mixture of compounds
A fossil fuel consisting of the remnants of ancient biomass
What is a hydrocarbon?
A compound made up exclusively of hydrogen and carbon atoms
What are alkanes?
Saturated hydrocarbons of a general formulation Cn H2n+2
Describe the combustion of hydrocarbons:
Exothermic reaction occurring when the hydrocarbons are reacted with oxygen
Complete combustion produces carbon dioxide and water
Incomplete combustion produces carbon or carbon monoxide and water
Describe the physical properties of alkanes:
In general boiling points and viscosity increase as molecules get bigger
Poor reactivity
Flamability decreases as molecules get bigger
Explain how fractional distillation of crude oil takes place:
Crude oil is heated and vaporized
Vapor rises up the fractioning column
The column is hotter at the bottom and cooler at the top
Hydrocarbons cool as they go up the column and condense at different heights as they have different boiling points
Large molecules - high boiling points - collected at the bottom
Small molecules - low boiling points - collected at the top
This gives fractions which can be used in various ways
What is cracking?
When large hydrocarbons are thermally broken down into smaller and more useful molecules
What type of reaction is cracking?
Thermal decomposition
What are the conditions for cracking?
Reactant heated to vapour and passed over a hot catalyst
How are the products of cracking used?
The products are alkanes and alkenes used as polymers and starting materials for synthesis
What is an alkene?
Unsaturated hydrocarbon
Cn H2n
What is the test for alkenes?
Add bromine water
Colour change occurs from Orange to colorless
Describe the combustion of alkenes?
They burn with smoky flames due to incomplete combustion
Give characteristics of methanol, ethanol, propanol and butanol:
Dissolven water to form a neutral solution
React with sodium to form hydrogen
Burn in oxygen
What does the oxidation of the alcohols lead to?
Carboxylic acids
What are some uses of alcohols?
Fuels
Solvents
Drinks
What type of acid is carboxylic acid?
A weak acid
What is a polymer?
A long chain molecule which is made by lots of smaller molecules joining together
