Crude oil and fuels

What is crude oil?

A non-renewable fossil fuel found underground

What is crude oil made of?

A mixture of many compounds, mainly hydrocarbons.

• Other compounds that contain elements like nitrogen, sulfur and oxygen need to be removed due to the atmospheric pollution they cause when burnt

What is the purpose of fractional distillation?

Splits up its components into different fractions suitable for different uses

How does fractional distillation work?

• Hydrocarbons boil and rise up the fractioning tower, where temperature decreases with increasing height

• Hydrocarbons reach the trays at fractions cool enough for them to condense into liquids

• Liquids with highest boiling points and larger molecular mass condense in trays near the bottom and vice versa

• Liquids are siphoned off at different levels and gases are collected near the top

*Fractions are a mixture of compounds and not just pure

What gas is collected at the top of the fractioning tower during the fractional distillation of hydrocarbons?

petroleum gas, hydrocarbon with the smallest molecular mass that does not condense

Why do hydrocarbons with larger relative Mr have higher boiling points?

Stronger IMF between molecules → more energy required to overcome FOA

What is natural gas?

A gaseous, odourless and colourless fossil fuel consisting mainly of CH4

What are biofuels?

Renewable energy source derived from plant and animal matter

What is the cycle of production for the burning of bioethanol?

1. Sugarcane is harvested

2. Sugarcane is processed and fermented to produce bioethanol

3. Bioethanol burns to provide energy to power vehicles: CO2 is produced and released into the atmosphere during combustion

4. Sugarcane absorbs CO2 during photosynthesis to produce sugar, which offsets the CO2 produced when bioethanol is burnt

What is the combustion reaction in producing bioethanol?

• ethanol + oxygen -> carbon dioxide + water

• C2H5OH (l) + 3O2 (g) -> 2CO2 (g) + 3H2O (g)

What are the negative impacts of biofuels?

• Clearing land for farming reduces biodiversity and produces large amounts of CO2

• Fertilisers used when farming biofuels may pollute the environment

• Production and transportation of biofuels requires energy through the combustion of fossil fuels

• Using crops to produce biofuels increases the competition for food sources e.g. sugarcane, corn