P2 - Organic Chemistry Flashcards
What are hydrocarbons ?
Compounds that contain only hydrogen and carbon atoms.
What are alkanes ?
The simplest form of hydrocarbon, with a formula of C(n)H(2n+2), they’re a homologous series and are saturated compounds.
What is a homologous series ?
Group of organic compounds that react in a similar way.
What are saturated compounds ?
In alkenes it means each carbon atom forms four single covalent bonds.
What are the first four alkanes ?
Methane(CH4), ethane(C2H6), propane(C3H8), butane(C4H10).
What is viscosity ?
Term relating to how runny or solid a substance is.
What are the properties of shorter hydrocarbon chains ?
They’re less viscous (more runny), more volatile - lower temperature at which it vaporises or condenses and lower boiling point, and the more flammable it is.
What is the equation for the complete combustion of a hydrocarbon in oxygen ?
Hydrocarbon + oxygen –> carbon dioxide + water (+energy)
What happens during combustion of hydrocarbons ?
Both the hydrogen and carbon are oxidised (gain oxygen).
Why are hydrocarbons used as fuels ?
The amount of energy they release when they combust completely.
What is crude oil ?
A fossil fuel, formed from the remains of plankton that died millions of years ago and were covered by sediment - high temperatures and pressure and a long time turned them into crude oil.
What are non-renewable fuels ?
They take so long to make they’re being used up faster than they’re made - finite resources.
What is crude oil made of ?
Mixture of many hydrocarbons - most of which are alkanes, which can be separated by fractional distillation.
How can you separate the different compounds in crude oil ?
By fractional distillation.
How does fractional distillation work ?
Oil is heated to gas in furnace before entering the fractionating column where as it rises through fractions different hydrocarbons will condense when they reach the fraction of the right temperature.
