8 1 fuels

Crude oil is a mixture of different hydrocarbons.

A hydrocarbon is a compound made up of hydrogen and carbon only.

Crude oil is a finite resource as it is being used up much faster than it is being formed.

Crude oil formed over millions of years from the effects of high pressures and temperatures on the remains of plants and animals.

Products from crude oil can be polymers, lubricants, solvents, detergents and adhesives.

True. Crude oil is a mixture containing different sized hydrocarbon molecules.

True. Each fraction in crude oil consists of groups of hydrocarbons with similar chain lengths.

Fractional distillation is the process of separating the different fractions of crude oil based on their boiling points.

True. The size and length of each hydrocarbon molecule determines which fraction it will be separated into.

False. As you move up a fractionating column, the temperature decreases.

As the number of carbon atoms increases, the viscosity of the liquid increases.

As the molecular size increases, the volatility of a hydrocarbon liquid decreases.

Viscosity is the ease of flow of a liquid.

Liquefied petroleum gas is used for domestic heating & cooking.

True. Kerosene is used as jet fuel (paraffin).

Diesel is used in diesel engines (gas oil).

Heavy fuel oil is used for ships & power stations.

The fraction used for surfacing roads is bitumen.

Fractions condense inside the fractionation tower because their vapours rise and reach a point where the temperature is below their boiling point.

As the molecules get larger, the intermolecular forces of attraction between the molecules becomes greater so more energy is needed to overcome them.

A homologous series is a family or group of organic compounds that have similar features and chemical properties due to having the same functional group.

All members of a homologous series have:

A functional group is a specific group of atoms within a molecule that determines the chemical properties of that molecule.

As the molecules get larger in a homologous series, the boiling points gradually increase due to greater intermolecular forces of attraction.

False. Compounds in the same homologous series have similar chemical properties

The products of complete combustion of hydrocarbons are carbon dioxide and water.

Incomplete combustion occurs when there is insufficient oxygen to burn the fuel completely.

The products of incomplete combustion are carbon monoxide, carbon (soot) and water.

Carbon monoxide binds well to haemoglobin, preventing it from binding to oxygen and transporting oxygen to organs.

False. Carbon dioxide is a pollutant causing global warming and climate change.

Incomplete combustion occurs in some appliances such as:

The symbol equation for the complete combustion of propane is: C3H8 + 5O2 → 3CO2 + 4H2O

The balanced symbol equation for the incomplete combustion of ethane is: C2H6 + 2.5O2 → 2CO + 3H2O

Three gases that the burning of fossil fuels releases:

A fuel is a substance that is burned to release heat / thermal energy

A common impurity in fuels that contributes to acid rain is sulfur. Nitrogen is not accepted.

Nitrogen oxides are formed in the high pressure and temperature conditions of internal combustion engines and blast furnaces.

The equation for the oxidation of sulfur is: S (s) + O2 (g) → SO2 (g)

Acid rain is formed by nitrogen and sulfur oxides dissolve in rainwater to form nitric acid and sulfuric acid, respectively.

Harmful effects of sulfur dioxide include:

Catalytic converters contain transition metal catalysts that convert pollutant gases to less harmful substances through redox reactions.

The equations for the reduction of nitrogen oxides are: 2NO → N2 + O2 2NO2 → N2 + 2O2

Two gases that contribute to acid rain are nitrogen dioxide and sulfur dioxide.

During combustion, the sulfur impurities in the fossil fuels get oxidised / react with oxygen to form sulfur dioxide.

The equation to show the formation of acid rain, H2SO4 (aq), from sulfur dioxide, water and oxygen is: 2SO2 (g) + O2 (g) + 2H2O (l) → 2H2SO4 (aq)

The symbol equation for the reaction of hydrogen with oxygen is: 2H2 + O2 → 2H2O

Advantages of using hydrogen as a fuel are:

The disadvantages of using hydrogen as a fuel are:

The type of reaction which occurs when hydrogen and oxygen react to form water is exothermic or combustion.

A fuel is a substance which when burned, releases heat energy

Fossil fuels include:

The main compound in natural gas is methane, CH4.

The type of fuel that provides most of the world's energy is fossil fuels.

The purpose of cracking is to convert surplus unwanted fractions of crude oil, such as kerosene and diesel oil, into more useful fractions like petrol (gasoline), alkenes, and hydrogen.

True. The demand for certain fractions outstrips the supply, which is why cracking is necessary to convert surplus unwanted fractions into more useful ones.

The two methods used for cracking alkanes are:

False. Cracking is an endothermic reaction.

The equation for the cracking of decane to produce octane and ethene is: C10H22 → C8H18 + C2H4

True. Alkanes are saturated compounds, and alkenes are unsaturated compounds.

The catalyst used in catalytic cracking is:

False: Cracking is a type of thermal decomposition reaction.

True. Long chain fractions are in high supply but in low demand. This explains why they are cracked into more useful, shorter chain alkanes and alkenes.

Examples of longer chain fractions of crude oil are:

A long chain hydrocarbon is cracked to form short chain alkanes and short chain alkenes.