Crude oil, hydrocarbons & alkanes

Crude oil is a mixture of hydrocarbons.

The majority of hydrocarbons in crude oil belong to one homologous series.

Give the name of this series.

When hydrocarbons undergo combustion, water is produced.

Draw a dot and cross diagram of a molecule of water.

One compound in crude oil contains 0.96 g of carbon atoms combined with 0.32 g of hydrogen atoms.

Calculate the empirical formula of this compound.

(relative atomic masses: C = 12, H = 1.0)

*(d) Crude oil is separated into useful products called fractions using fractional distillation.

Figure 14 shows a fractional distillation column and the fractions kerosene and fuel oil.

Kerosene and fuel oil have different uses depending on their properties.

Describe the properties and uses of kerosene and fuel oil. Include in your answer

• the difference in boiling point

• the difference in viscosity

• the difference in ease of ignition

• their uses and how fuel oil can be converted into kerosene.

This question is about carbon and some carbon compounds.

Two forms of pure carbon are graphite and Buckminsterfullerene.

Explain why graphite is used as a lubricant.

Calculate the mass, in kg, of five moles of Buckminsterfullerene, C₆₀.

(relative atomic mass: C = 12)

A molecule in an homologous series has the formula C₉H₂₁N.

What is the formula of the next molecule in this homologous series?

A Bunsen burner burns methane gas, CH₄.

A student investigates the time taken to heat up a beaker of water using this Bunsen burner.

Figure 9 shows the apparatus used.

The student sees that a large amount of carbon forms as a black solid on the underside of the gauze.

The teacher said that the investigation would be improved if no carbon forms.

Explain what the student should do to stop carbon forming on the underside of the gauze.

*(d) Natural processes and human activities change the amount of carbon dioxide in the atmosphere.

Figure 10 shows the concentration of carbon dioxide in the atmosphere measured in one location and the mean global temperature from 1960 to 2000.

Evaluate whether the data in Figure 10 shows that the change in the amount of carbon dioxide is leading to climate change.

Your answer should include

• the natural processes that change the amount of carbon dioxide in the atmosphere

• the human activities that change the amount of carbon dioxide in the atmosphere

• how carbon dioxide contributes to the greenhouse effect and climate change.

Figure 9 shows the structure of one molecule of three different compounds, X, Y and Z.

The molecules of the compounds shown in Figure 9 all contain the same number of carbon atoms.

Give the number of carbon atoms in a molecule of compound X.

Compound X contains carbon and one other element.

Give the name of the other element in compound X.

Which of the compounds in Figure 9 is a hydrocarbon?

Which of the compounds in Figure 9 have the same molecular formula?

Figure 10 shows where fractions are produced in the fractional distillation of crude oil.

Complete the sentences about fractions obtained from crude oil.

The fraction with the smallest molecules is called_........ .

Compared to petrol, the boiling point of kerosene is_........ .

When petrol burns, one product is_........ .

When some impure hydrocarbon fuels are burned, sulfur dioxide is one of the products.

Some sulfur dioxide gas is dissolved in water to form solution W.

When solution W is added to sodium hydroxide solution of pH 12

• the pH changes

• the temperature increases.

Explain how the pH changes and why the temperature increases.

The structure of one molecule of compound L is shown in Figure 12.

State what the lines between the atom symbols represent in Figure 12.

Explain why compound L is an alkene.

1 molecule of compound L has a mass of 9.302 × 10^–23g.

82,500 molecules of compound L combine to form 1 polymer molecule.

Calculate the mass of this polymer molecule.

Some naturally occurring molecules are polymers.

Draw one straight line from each natural polymer to its monomer.

*(c) Figure 13 shows information about four compounds, E, F, G and H.

The compounds are in no particular order

• butane

• carbon dioxide

• ethane

• ethene.

Use all of the information in Figure 13 to identify which of the four compounds, E, F, G and H, is

• butane

• carbon dioxide

• ethane

• ethene.

You must give reasons for your choices.

Most hydrocarbons found in fossil fuels are members of the alkane homologous series.

State two features of an homologous series.

Which molecule is in the same homologous series as CH₄?

A fossil fuel contains carbon and sulfur.

Explain how the products of the complete combustion of this fossil fuel would affect the environment.

Incomplete combustion of fuels may produce carbon monoxide.

Write the balanced equation for the incomplete combustion of heptane, C₇H₁₆, where all of the carbon atoms form carbon monoxide.

Figure 8 shows one molecule of a compound obtained from crude oil.

Give the names of the two elements in this molecule.

What is the molecule in Figure 8?

What is the relative formula mass of the compound in Figure 8?

(relative atomic masses: H = 1.0, C = 12)

Crude oil can be separated into different fractions.

Draw one straight line from each fraction to a use of that fraction.

Hydrogen chloride gas and sulfur dioxide gas are dissolved in separate test tubes of water. Blue litmus paper is dipped into each test tube.

State and explain the colour change you would observe in each test tube.

Figure 8 shows some information about the composition of pollutant exhaust gases from the engines of two different vehicles.

Give two ways in which the data in Figure 8 shows that the diesel engine is more damaging to the environment than the petrol engine.

Explain, using information from Figure 8, one way in which the diesel engine is less damaging to the environment than the petrol engine.

Which statement about the members of the alkane homologous series is correct?

Which one of the following hydrocarbons belongs to the same homologous series as octane, C₈H₁₈?

Write the balanced equation for the complete combustion of octane, C₈H₁₈.

Diesel oil is a mixture of hydrocarbons that can be obtained from crude oil.

State the name of the process used to separate diesel oil from crude oil.

Diesel oil contains alkanes. These alkanes are part of an homologous series.

Which statement about compounds in this homologous series is true?

When fuels such as diesel oil are burned, the high temperatures produced can cause nitrogen and oxygen in the air to form the pollutant nitrogen dioxide.

Complete the balanced equation for the reaction.

Explain how the greenhouse effect is caused by the gases produced by the complete combustion of diesel oil.

*(e) Diesel oil can contain impurities of sulfur. Burning diesel oil containing impurities of sulfur can result in acid rain. Acid rain is harmful to the environment.

Explain how acid rain is formed and the harm it can do.

Diesel oil is a mixture of hydrocarbons that can be obtained from crude oil.

State the name of the process used to separate diesel oil from crude oil.

Diesel oil contains alkanes. These alkanes are part of an homologous series.

Which statement about compounds in this homologous series is true?

When fuels such as diesel oil are burned, the high temperatures produced can cause nitrogen and oxygen in the air to form the pollutant nitrogen dioxide.

Complete the balanced equation for the reaction.

Explain how the greenhouse effect is caused by the gases produced by the complete combustion of diesel oil.

Ethanol can be produced by the fermentation of glucose solution.

Which of these shows the word equation for the fermentation of glucose solution?

The names and formulae of the first four alcohols in the homologous series of alcohols are given in Figure 12.

Pentanol is the next member of this series. A molecule of pentanol contains five carbon atoms.

Suggest the formula of a molecule of pentanol.

Draw the structure of a molecule of ethanol. Show all bonds.

Ethanol is present in alcoholic drinks, such as wine.

When a bottle of wine is left open some of the ethanol reacts with the oxygen in the air to form ethanoic acid, CH₃COOH, and water.

Complete the equation for this reaction.

Which calculation shows the percentage by mass of hydrogen in ethanoic acid?

(relative atomic mass of hydrogen, H = 1, relative formula mass of ethanoic acid, CH3₃COOH = 60)

*(d) Polymers have many uses. However, the disposal of polymers after use can be a problem. The uses of polymers are related to their properties.

Some uses of three common polymers are given in Figure 13.

Discuss the reasons for using these polymers in the ways shown in Figure 13 and the problems in disposing of these polymers.

Figure 10 shows a flask fitted with a cotton wool plug. The flask contains an aqueous solution of a carbohydrate.

State two steps that need to be taken to turn the solution of the carbohydrate in the flask into a solution of ethanol.

The apparatus in Figure 11 is used to increase the concentration of the dilute solution of ethanol.

This apparatus did not produce a very concentrated solution of ethanol.

Describe how the apparatus can be altered to produce a more concentrated solution of ethanol.

The equation for the fermentation of a carbohydrate is

Calculate the maximum mass of carbon dioxide that could be produced if 135 g of this carbohydrate is fully fermented.

(relative formula masses: CO₂ = 44; C₆H₁₂O₆ = 180)

*(c) Figure 12 shows information about some compounds in the same homologous series.

Explain, using the data in Figure 12, why these compounds belong together in the same homologous series.

Most of the fuels used today are obtained from crude oil.

Which statement about crude oil is correct?

Crude oil is separated into several fractions by fractional distillation. Two of these fractions are kerosene and diesel oil.

State a use for each of these fractions.

Figure 13 shows where the fractions kerosene and diesel oil are produced in the fractionating column.

Kerosene is obtained higher up the column than diesel oil. Kerosene and diesel oil fractions have slightly different properties.

Choose a property. State how this property for kerosene compares with the property for diesel oil.

Figure 14 shows the formulae of a molecule of butane and of a molecule of pentane. Butane and pentane are neighbouring members of the same homologous series.

H H H H
H H H H H

H H H H
H H H H H

butane pentane

Figure 14

Explain, using these formulae, why butane and pentane are neighbouring members of the same homologous series.

Butane has the formula C₄H₁₀.

Calculate the mass of carbon in 100 g of butane.

Give your answer to three significant figures.

(relative atomic masses: H = 1.00, C = 12.0; relative formula mass: C₄H₁₀ = 58.0)

You must show your working.

Butane burns completely in air to form carbon dioxide and water.

Write the word equation for this reaction.

Most of the fuels used today are obtained from crude oil.

Which statement about crude oil is correct?

Crude oil is separated into several fractions by fractional distillation. Two of these fractions are kerosene and diesel oil.

State a use for each of these fractions.

Figure 1 shows where the fractions kerosene and diesel oil are produced in the fractionating column.

Kerosene is obtained higher up the column than diesel oil. Kerosene and diesel oil fractions have slightly different properties.

Choose a property. State how this property for kerosene compares with the property for diesel oil.

Figure 2 shows the formulae of a molecule of butane and of a molecule of pentane. Butane and pentane are neighbouring members of the same homologous series.

H H H H
H H H H H

butane pentane

Figure 2

Explain, using these formulae, why butane and pentane are neighbouring members of the same homologous series.

Butane has the formula C₄H₁₀.

Calculate the mass of carbon in 100 g of butane.

Give your answer to three significant figures.

(relative atomic masses: H = 1.00, C = 12.0; relative formula mass: C₄H₁₀ = 58.0)

You must show your working.

(a) Nanoparticles are found in some sunscreens.

An atom has a radius of about 0.1 nm.

A nanoparticle might have a radius of about

A useful property of nanoparticles in sunscreens is that they

A nanoparticle has a surface area of 38 400 nm² and a volume of 51 200 nm³.

Calculate the surface area to volume ratio.

surface area to volume ratio = 1.00:_........

The molecules of three organic substances A, B and C are shown in Figure 6.

A small volume of bromine water is added to each of the substances A, B and C and the mixtures shaken. Explain why A and B decolourise bromine water but C does not.

Ethane, C₂H₆, is a hydrocarbon.

Draw a molecule of ethane showing all covalent bonds.

State why ethane is described as a hydrocarbon.

Crude oil is found in the Earth’s crust.

Which of the statements about crude oil is correct?

The substances ethane, C₂H₆, octane, C₈H₁₈, and pentadecane, C₁₅H₃₂, are all found in crude oil.

These substances

Use a word from the box to complete each of the sentences about the fractional distillation of crude oil.

Each word may be used once, more than once, or not at all.

The separation of crude oil into fractions occurs in a fractional distillation column.

Before crude oil is passed into the column it is_........ .

During the distillation, vapour rises up the column until it is cold enough for the

vapour to form a liquid. The vapour has been_........ .

Complete this sentence by underlining the correct answer in the box.

Compared with the fraction from the top of the column,

has more carbon atoms per molecule.

the fraction from the bottom of the column has a lower viscosity.

is easier to ignite.

When crude oil is separated into fractions, the amount of each fraction obtained rarely matches the demand for that fraction.

Figure 7 shows the relative amounts of four of the fractions obtained from a crude oil and the relative demand for each of these fractions.

State the fraction for which the relative amount obtained exceeds the relative demand.

In January 2015 the United Kingdom produced 850 000 barrels of crude oil per day. 45% of this crude oil was fuel oil.

Calculate the number of barrels of fuel oil present in the 850 000 barrels of crude oil.

Give your answer to two significant figures.

Ethanol can be used as a liquid fuel.

A student investigates how much heat energy is released when a known mass of ethanol is burned.

The apparatus is set up as shown in Figure 15.

A known volume of water is placed in a metal can. The temperature of the water is measured. The ethanol is ignited and placed under the beaker so that the flame is touching the beaker. The water is heated by the flame. The flame is extinguished. The final temperature of the water is measured.

The theoretical temperature rise for burning a given mass of ethanol is 82.4 °C.

In the experiment the actual temperature rise for burning this mass of ethanol was only 34.8 °C. One reason why the temperature rise is less than expected is that the ethanol does not burn completely.

Give a reason why, even if the ethanol burns completely, the actual temperature rise is much less than the theoretical value.

Explain how the method described above could be improved to give a temperature rise closer to the theoretical value.

The amount of heat energy used to raise the temperature of the water by 34.8 °C can be calculated using

heat energy = 210 × temperature rise

Calculate the amount of heat energy used.

heat energy =_........ (energy units)

Propanol and butanol are both members of the same homologous series as ethanol.

H H H
H H H H

H H H
H H H H

propanol butanol

Propanol and butanol can also be burned in the apparatus shown in Figure 15.

Give three reasons why ethanol, propanol and butanol are members of the same homologous series.

Ethanol can oxidise when exposed to air to produce ethanoic acid and water. Propanol can also oxidise in a similar reaction when it is exposed to air.

Write the word equation for the reaction when propanol oxidises when it is exposed to air.

What is the formula of the functional group in carboxylic acids?

Ethanol can be used as a liquid fuel.

A student investigates how much heat energy is released when a known mass of ethanol is burned.

The apparatus is set up as shown in Figure 3.

A known volume of water is placed in a metal can. The temperature of the water is measured. The ethanol is ignited and placed under the beaker so that the flame is touching the beaker. The water is heated by the flame. The flame is extinguished. The final temperature of the water is measured.

The theoretical temperature rise for burning a given mass of ethanol is 82.4 °C.

In the experiment the actual temperature rise for burning this mass of ethanol was only 34.8 °C. One reason why the temperature rise is less than expected is that the ethanol does not burn completely.

Give a reason why, even if the ethanol burns completely, the actual temperature rise is much less than the theoretical value.

Explain how the method described above could be improved to give a temperature rise closer to the theoretical value.

The amount of heat energy used to raise the temperature of the water by 34.8 °C can be calculated using

heat energy = 210 × temperature rise

Calculate the amount of heat energy used.

heat energy =_........ (energy units)

Ethanol can oxidise when exposed to air to produce ethanoic acid and water. Propanol can also oxidise in a similar reaction when it is exposed to air.

Write the word equation for the reaction when propanol oxidises when it is exposed to air.

What is the formula of the functional group in carboxylic acids?

Crude oil is a complex mixture of substances.

Crude oil can be separated into useful fractions by fractional distillation.

Figure 7 shows a fractional distillation column and the fractions produced when a sample of crude oil is distilled.

The properties of these fractions vary from the top of the column to the bottom of the column.

Which of the following is a trend in a property of the fractions obtained from the top of the column to those obtained from the bottom?

Most of the substances in crude oil are alkanes.

Explain why alkanes are described as hydrocarbons.

Figure 8 shows a graph of the boiling points of some alkanes against the number of carbon atoms in one molecule of each alkane.

Explain the pattern shown by this graph.

Use the information in Figure 9 to give the name of the fraction that is most likely to need to be cracked.

_........

In a cracking reaction, reactants are heated to form products. This reaction is endothermic.

On the axes provided, draw the reaction profile of this reaction. Label the energy of the reactants, the energy of the products and the activation energy of the reaction.

Dodecane, C₁₂H₂₆, can be cracked to form useful products.

Complete the equation for the cracking of dodecane by filling in the formula of the single molecule needed to balance the equation.