Fuels Flashcards
All 38 cards in this deck
What is a hydrocarbon?
A compound that contains carbon and hydrogen only.
What is crude oil?
A complex mixture of hydrocarbons.
It is a finite resource.True or false? Crude oil is a mixture of the elements hydrogen and carbon.
False. Crude oil is a mixture of compounds (hydrocarbons), not of elements.
Apart from fuels, what is crude oil an important source of?
Feedstock for the petrochemical industry.
True or false? In crude oil the carbon atoms are arranged in chains or in rings.
True. Most molecules are chains, but some contain rings of carbon atoms.
Which property of hydrocarbons is used to separate crude oil by fractional distillation?
Their boiling points.
Where in the fractionating column are hydrocarbons with the highest boiling points collected?
At the bottom of the column.
True or false? Fractional distillation separates crude oil into pure single compounds.
False. It separates crude oil into fractions, which are simpler, more useful mixtures.
Name the crude oil fraction used as fuel for cars, and the fraction used as fuel for aircraft.
Petrol for cars; kerosene for aircraft.
Give a use of the bitumen fraction.
Surfacing roads (and roofs).
How do hydrocarbons with longer carbon chains compare with shorter ones in boiling point, viscosity and ease of ignition?
Higher boiling point, higher viscosity and harder to ignite.
What is a homologous series?
A series of compounds with the same general formula, differing by from neighbouring members, with a gradual variation in physical properties and similar chemical properties.
What is the general formula of the alkanes?
True or false? Compounds in the same homologous series have the same molecular formula.
False. They have the same general formula but different molecular formulae.
What are the products of the complete combustion of a hydrocarbon?
Carbon dioxide and water.
Energy is given out.Why does incomplete combustion of a hydrocarbon occur?
A limited supply of oxygen.
Which two extra products can be formed by the incomplete combustion of a hydrocarbon?
Carbon (soot) and carbon monoxide.
How does carbon monoxide act as a toxic gas?
It binds to haemoglobin in red blood cells, so the blood carries less oxygen.
Give two problems caused by incomplete combustion in appliances such as gas boilers.
Carbon monoxide is toxic and can kill (it has no smell or colour); soot blackens surfaces, blocks pipes and can cause fires.
Why is sulfur dioxide produced when some hydrocarbon fuels are burned?
The fuels contain sulfur impurities, which burn (react with oxygen) to form sulfur dioxide.
What is formed when sulfur dioxide dissolves in rain water?
Acid rain.
Give two problems caused by acid rain.
It makes lakes and rivers acidic, killing fish and plants; it damages/erodes buildings and statues made of limestone and corrodes metals.
Why are oxides of nitrogen formed inside engines?
The high temperature makes nitrogen and oxygen from the air react together.
True or false? The nitrogen that forms oxides of nitrogen in an engine comes from the fuel.
False. It comes from the nitrogen in the air drawn into the engine.
What is the only product of burning hydrogen as a fuel?
Water.
hydrogen + oxygen → waterGive two disadvantages of using hydrogen rather than petrol as a fuel in cars.
Hydrogen is hard to store and transport (it is a gas, stored under pressure, and is explosive), and there are few hydrogen filling stations.
Give two advantages of using hydrogen rather than petrol as a fuel in cars.
It produces no carbon dioxide, carbon monoxide or soot, and it can be made from water rather than from a finite fossil fuel.
True or false? Petrol, kerosene and diesel oil are renewable fuels.
False. They are non-renewable fossil fuels obtained from crude oil, which is a finite resource.
Methane is a non-renewable fossil fuel found in which resource?
Natural gas.
What is cracking?
Breaking down larger, saturated hydrocarbon molecules (alkanes) into smaller, more useful molecules, some of which are unsaturated (alkenes).
Why is cracking necessary?
The supply of long-chain fractions is greater than the demand, while demand for short-chain fuels such as petrol is greater than the supply.
True or false? All of the products of cracking an alkane are alkanes.
False. Some products are unsaturated hydrocarbons (alkenes).
Give a use of the fuel oil fraction.
Fuel for large ships and in some power stations.
Give a use of the diesel oil fraction.
Fuel for some cars and trains (also lorries, tractors).
Give a use of the gases fraction from crude oil.
Domestic heating and cooking.
Give two harmful effects of the oxides of nitrogen released from engines.
They dissolve in water in clouds to cause acid rain, and at ground level they cause photochemical smog, which leads to breathing problems.
How does the temperature vary inside a fractionating column?
It is hottest at the bottom and gets cooler towards the top (a temperature gradient).
Most of the hydrocarbons in crude oil and its fractions belong to which homologous series?
The alkanes.