C1 - Crude Oil & Fuels Flashcards
What are alkanes?
Saturated hydrocarbons.
What is crude oil?
A mixture of hydrocarbons and other compounds.
How are the compounds in crude oil crude oil separated?
Fractional distillation.
Why isn’t crude oil useful?
There are too many compounds that have different boiling points.
What method is used to separate the compounds in crude oil?
Fractional distillation.
Give the first five alkanes and their respective symbols.
- Methane (CH4)
- Ethane (C2H6)
- Propane (C3H8)
- Butane (C4H10)
- Pentane (C5H12)
What is the formula for alkane compounds?
CnH(2n+2)
How does the size of a hydrocarbon molecule affect its boiling point?
Smaller molecules tend to:
- have lower boiling points
- be more volatile
- be less viscous
- be more flammable.
What makes a fraction useful as a fuel?
Lighter fractions are better fuels because they ignite easily, burn well with less smoke.
Describe fractional distillation.
The crude oil is vaporised at 400C then fed into the tower. The residue goes straight out of the bottom of the tower whilst the hot gases rise. The temperature decreases going up the column.Once a fraction has reached its boiling point going up the tower it will condense and the liquid is collected then processed.
What are the products of combustion of a hydrocarbon and why?
Water and carbon dioxide because the carbon and hydrogen are completely oxidised.
What pollutants are produced when burning fuels?
- Sulfur impurities form sulfur dioxide.
- In insufficient oxygen, carbon monoxide or soot can be formed.
- At high temperatures, nitrogen oxide are formed.
Give the symbol equation of propane combustion.
C3H8 + 5O2 —> 3CO2 + 4H2O
What are the consequences for the environment of burning fossil fuels?
- Sulfur dioxide and nitrogen oxide produce acid rain.
- Carbon dioxide is a greenhouse gas.
Give two ways pollution can be reduced.
- Sulfur can be removed before being burnt.
- Catalytic converters.
How do catalytic converters work?
Metal catalysts make carbon monoxide and nitrogen oxides react to produce carbon dioxide and nitrogen.
Why are catalytic converters expensive?
They contain precious metals.
How are catalytic made efficient?
They have a large surface area of the catalyst.
What do particulates from unburnt hydrocarbons cause?
Global dimming.
What are biofuels?
A renewable source of energy made from oils extracted from plants.
Give five advantages of using biodiesel.
- It’s less harmful to plants and animals.
- It burns cleanly.
- Biodiesel will eventually become cheaper than petrol.
- The process is CO2 neutral.
- Useful products are made when producing biodiesel.
Give three disadvantages of biodiesel.
- Large areas of farm are needed which could be used to grow food.
- Habitats could be destroyed.
- It freezes before diesel does and goes sticky at high temp.
