Fuels and Atmospheric Science Flashcards
What is crude oil?
A fossil fuel that is formed over millions of years from ancient remains of marine organisms, it is an important source of useful substances and it is a finite resource
What are hydrocarbons?
Compounds of carbon and hydrogen atoms only
What bonds can carbon atoms make in hydrocarbons?
Carbon-carbon and carbon-hydrogen
In terms of hydrocarbons what is crude oil?
A complex mixture of hydrocarbons with carbon atoms in chains or rings
What is a finite resource?
A resource that will run out because it is no longer being made or it is being made extremely slowly, crude oil is a finite resource because it takes millions of years to form
Why can crude oil be separated using fractional distillation?
Because its different hydrocarbons have different boiling points
How does fractional distillation work to separate crude oil?
- Crude oil is heated and vapours begin to rise up the fractionating column
- The column is hot at the bottom and cool at the top
- Each fraction condenses where it becomes cool enough and is piped out of the column
- The gases fraction does not condense and leaves at the top
- The bitumen fraction does not evaporate and leaves at the bottom
- The other fractions are liquid at room temperature so they’re useful as fuels
What happens to hydrocarbons in terms of physical properties as the number of hydrogen and carbon atoms increases?
- The strength of the intermolecular forces increases so more energy must be transferred to overcome these forces meaning the boiling point increases
What happens to the boiling point, ease of ignition and viscosity of a hydrocarbon as the number of hydrogen and carbon atoms increase?
- The boiling point increases
- The ease of ignition decreases, hydrocarbons become less flammable as the number of hydrogen and carbon atoms increase
- The viscosity increases, the hydrocarbon becomes more ‘thick’
What are most hydrocarbons from crude oil?
Alkanes
In a homologous series what does the molecular of the neighbouring member differ by?
CH2, neighbouring members also show a gradual variation in physical properties, for examples as CH2 is added the boiling point of that hydrocarbon increases
What happens to alkanes when they react with oxygen?
They undergo complete combustion
What is the general word equation for complete combustion?
Hydrocarbon + oxygen → carbon dioxide + water
What is the general word equation for incomplete combustion?
Hydrocarbon + oxygen → carbon monoxide + carbon + water
What is the general formula for an alkane?
Cn+H2n+2