Organic Chemistry Flashcards
What is crude oil
A finite resource made of a mixture large number of compounds, mostly hydrocarbons- usually alkanes
What is a hydrocarbon?
Compound made of hydrogen and carbon
How is crude oil formed?
Plants and animals die and fall to sea bed
Layers of sand and mud build on top
Pressure and high temp causes oil to form
Oil obtained by drilling
What can be used to separate hydrocarbons in crude oil
Fractional distillation
How does fractional distillation work?
E+H/E+C/L/H
Crude oil extracted and heated in a fractionating column.
The liquid evaporates and vapour condenses at different temps.
Fraction with the lowest boiling point comes out at top of column
Fraction with highest boiling point comes out at bottom of column
Which properties of hydrocarbons depend on size of molecule?
Boiling point, viscosity, flammability
What happens to the boiling points of hydrocarbons as you increase the chain length?
Boiling point increases as you increase the chain length.
because: when there are more carbon atoms in the chain. there are more intermolecuar forces, so it is harder to break them a part.
What happens to the viscosity of hydrocarbons as you increase the chain length?
viscosity increases as you increase the chain length - less it flows. Methane is the most runny
What happens to the flammability of hydrocarbons as you increase the chain length?
Flammability decreases as length of chain increases. Methane is most flammable
What is cracking?
Breaking down long chain hydrocarbons to make smaller more useful molecules (produces a mixture of short chain alkanes and some alkenes)
2 types of cracking
Thermal cracking (high temps+ pressure, NO catalyst)
catalytic cracking (lower temp, low pressure, YES catalyst)
Conditions of cracking
High temperature
(Moderate pressure)
Zeolite catalyst- contains aluminium oxide and silicone oxide
Why are large hydrocarbons cracked?
Higher demand for shorter hydrocarbons, because shorter are useful for oil
What happens when you react alcohols with sodium?
Alcohols react with sodium to produce a salt and hydrogen gas.
Example: sodium ethoxide + hydrogen.
What happens when you put alcohols in water?
Alcohols fully dissolve in water.
The shorter the chain length, the more soluble
What happens when you burn alcohols in air?
Alcohols completely combust to form carbon dioxide and water.
Example: C2H5OH + 3O2 → 2CO2 + 3H2O.
What happens to alcohols when you oxidise them?
Oxygen reacts with the alcohol, forming a carboxylic acid
Example: ethanol + oxidising agent → ethanoic acid + water
What are the uses of methanol?
Feedstock (raw material to make plastics) drugs and solvents.
Also can be mixed with ethanol to form methylated spirit
What are the applications of ethanol in manufacturing?
Ethanol is used as a solvent in perfumes, cosmetics, pharmaceuticals, varnishes, detergents, inks, and coatings.
Also present in many common beverages
How can you make ethanol?
Ethanol can be made by fermentation of sugar solutions using yeast.
What are the conditions for fermentation?
Fermentation occurs anaerobically at 35°C with sugar and yeast dissolved in water.
How does modern life depend on the uses of hydrocarbons?
What’s the monomer for cellulose and starch?
Glucose
