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HydrocarbonsOxford AQA IGCSE Chemistry: Flashcards

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What is a hydrocarbon?

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What is a hydrocarbon?
A molecule made up of hydrogen and carbon atoms only
What is the general formula for an alkane?
CnH2n+2
What does it mean for a hydrocarbon to be saturated?
All the carbon-carbon bonds are single covalent bonds
Name the first three alkanes.
Methane (CH4), ethane (C2H6), propane (C3H8)
What is the molecular formula of methane?
CH4
What is the molecular formula of propane?
C3H8
How does boiling point change as hydrocarbon chain length increases?
Boiling point increases
How does viscosity change as hydrocarbon chain length increases?
Viscosity increases (the liquid gets thicker)
How does flammability change as hydrocarbon chain length increases?
Flammability decreases
Why does boiling point increase with chain length?
Longer molecules have stronger intermolecular forces, needing more energy to separate them
What process separates crude oil into fractions?
Fractional distillation
Where are fractions with short chain lengths collected in a fractionating column?
Near the top, where it is cooler
Where are fractions with long chain lengths collected in a fractionating column?
Near the bottom, where it is hotter