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Chemistry 1- Separating crude oils (Crude oil- mixture of compounds called…
Chemistry 1- Separating crude oils
Crude oil- mixture of compounds called hydrocarbons- many useful materials can be produced from it
Crude oil can be separated into different fractions using fractional distillation- some can be used as fuels
Crude oils form naturally over years from the remains of living things
Most compounds in crude oil are hydrocarbons
Hydrocarbons only contain hydrogen and carbon- joined by covalent bonds
Different types of hydrocarbon- most in crude oil alkanes
Alkanes- family of hydrocarbons sharing the same general formula
CnH2n+2- general formula means number of hydrogen atoms in an alkane is double the number of carbon atoms plus 2
Methane- CH4, ethane- C2H6
Alkane molecules can be represented by displayed formula, in displayed formula each atom displayed as symbol (C or H), each covalent bond by straight line
Methane- CH4
Ethane- C2H6
Propane- C3H8
Butane- C4H10
Distillation- process that can separate a pure liquid from a mixture of liquids- Works when liquids have different boiling points
Distillation commonly used to separate ethanol (alcohol in alcoholic drinks) from water
Mixture heated in flask-ethanol lower boiling point so it evaporates first-ethanol vapour cooled and condensed inside condenser to form a pure liquid
Thermometer-shows boiling point of pure ethanol liquid- once ethanol gone- temperature rises and water evaporates
Heating>Evaporating>Cooling>Condensing
Fractional distillation different to distillation as it separates mixture into fractions
Tall column fitted above mixture- several condensers at different heights- hot at bottom cool at top
Substances with high boiling points condense at bottom, lower boiling points condense at top
Crude oil evaporates, vapours condense at different points- each fraction contains hydrocarbon atom with similar number of carbon atoms
Gases leave at top of column, liquids middle, solids bottom
Up fractional distillation column hydrocarbons have lower boiling points, lower viscosity (flow easier) , higher flammability
