C9 - Crude oil and fuels Flashcards
C9 - Describe the properties of alkanes
Homologous series - a group of chemicals with similar formulas and properties.
Their names all end in ane.
Do not contain a double bond.
Saturated hydrocarbons.
General formula CnH2n+2
First five in the series: methane, ethane, propane, butane and pentane.
C9 - Describe the properties of alkenes
Homologous series - a group of chemicals with similar formulas and properties.
Their names all end in ene.
Contain a double bond.
Unsaturated hydrocarbons.
General formula CnH2n
First five in the series: ethene, propene, butene and pentene and hexene.
C9 - How does chain length affect properties?
Short chain
Low boiling point
High volatility
Low viscosity (very runny)
High flammability
Long chain
High boiling point
Low volatility
High viscosity (thick)
Low flammability
C9 - What are the word and symbol equations for Combustion?
Complete combustion:
Hydrocarbon (ethane) + oxygen → carbon dioxide + water
2C2H6 + 7O2 → 4CO2 + 6H2O
Incomplete combustion:
Hydrocarbon (ethane) + oxygen → carbon monoxide + carbon + water
C2H6 + 2O2 → CO + C + 3H2O
C9 - Explain how fractional distillation is used to separate the hydrocarbons within crude oil.
Crude oil is heated and vapourised.
Passed through a fractionating column.
The fractionating column has a temperature gradient - it is hot at the bottom and cold at the top.
Large hydrocarbons collect at the bottom of the chamber as they have high boiling points.
Small hydrocarbons collect at the top of the chamber as they have low boiling points.
The other hydrocarbons collect and condense between the bottom and top depending on their boiling points.
C9 - Cracking hydrocarbons
The process of breaking larger, less useful hydrocarbons down into smaller more useful ones.
Cracking involves:
A catalyst
Steam
Alkanes and alkenes are the products of cracking
C9 - Testing for hydrocarbons
Can be done using bromine water, which is usually orange.
An alkene will turn orange Bromine water colourless
An alkane will not react and the Bromine water will stay orange.
