Alkenes

Figure 4 shows the structure of molecules of three compounds, A, B and C.

Explain which compound, A, B or C, is an alkene.

What is the empirical formula of compound B ?

The test to distinguish between compounds B and C involves shaking separate samples of each compound with an orange solution.

The label on the orange solution is shown in Figure 5.

State the meaning of the hazard symbol shown.

Name the orange solution used to distinguish between compounds B and C.

What is the final appearance of the mixture when compound B is shaken with a few drops of the orange solution?

The molecular formula of compound A is C₄H₁₀O.

A sample of compound A undergoes complete combustion to form carbon dioxide and water.

Explain why this reaction is an oxidation reaction.

Calculate the mass of water formed from the complete combustion of 74 g of compound A, C₄H₁₀O.

(relative formula masses: C₄H₁₀O = 74, H₂O = 18)

A student carries out a flame test on a salt. The student observes a yellow flame.

Which ion is in the salt?

A molecule of a yellow substance is shown in Figure 1.

What is the formula of this molecule?

A bottle of this substance is labelled with the hazard symbol in Figure 2.

State the danger associated with the contents of this bottle.

Yellow bananas emit ethene gas, C₂H₄.

Draw one molecule of ethene, showing all covalent bonds.

Gold has a yellow colour.

A gold nanosphere has a surface area of 305 nm². The surface area to volume ratio is 1: 4.60.

Calculate the volume, in nm³, of the gold nanosphere.

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.

Figure 13 shows the apparatus used to burn different alcohols.

The mass of each alcohol required to raise the temperature of the water by 40 °C is found.

State one variable, apart from the volume of water, that should be kept the same when each alcohol is burned.

It is found that 1.6 g of ethanol is used to raise the temperature of water by 40 °C.

Calculate the number of moles of ethanol used. Give your answer to two significant figures. (relative formula mass: ethanol = 46)

number of moles =_........

The mass of ethanol used to raise the temperature of the water by 40 °C is higher than the theoretical value.

The experiment is repeated and the same result obtained.

Give a reason why the mass of ethanol used is higher than expected.

Poly(phenylethene) is an addition polymer.

Figure 14 shows part of the poly(phenylethene) molecule formed in the addition reaction between three phenylethene monomer molecules.

Draw the structure of one phenylethene monomer molecule.

Explain what is seen when a few drops of bromine water are shaken with phenylethene.

Poly(phenylethene) is an addition polymer.

Polyesters are condensation polymers.

Describe the differences between the type of monomer molecules used to form addition polymers and the type of monomer molecules used to form condensation polymers.

Figure 12 shows the structure of the molecules of three organic compounds.

Each molecule in Figure 12 contains a different functional group.

Circle the alkene functional group in propene.

Propene reacts with bromine water.

Complete the equation for the reaction of propene with bromine by drawing the structure of a molecule of the product.

H H

H H

propene bromine product

Propanoic acid reacts with calcium carbonate, CaCO₃, to form calcium propanoate, Ca(C₂H₅COO)₂, and two other products.

Name the two other products.

*(b) Glucose, C₆H₁₂O₆, is a carbohydrate.

A dilute solution of ethanol can be produced from glucose by fermentation.

The dilute solution of ethanol can then be processed to form a concentrated solution of ethanol.

Describe how the fermentation of glucose is carried out and how the dilute solution of ethanol produced can then be processed to form a concentrated solution of ethanol.

You may include diagrams in your answer.

The structure of one molecule of a compound is shown in Figure 10.

What is the molecular formula of the compound in Figure 10?

The compound in Figure 10 is an unsaturated hydrocarbon.

State why the compound is described as an unsaturated hydrocarbon.

Many molecules of the compound in Figure 10 combine to form substance Y. Figure 11 shows part of a molecule of substance Y.

H H H H H H H H

Figure 11

What type of substance is Y?

One molecule of the compound in Figure 10 has a mass of 6.9810^–23g.

64 800 of these molecules combine to form one molecule of Y.

Calculate the mass of this molecule of Y in g.

*(d) Alkanes can be burned in air. Different products can be formed as the combustion of alkanes can be complete or incomplete.

An investigation was carried out to compare the energy released when the first four alkanes in the homologous series were burned. Equal amounts of these alkanes were burned to heat 100 cm³ of water. The temperature change for each alkane is shown in Figure 12.

Discuss the complete and incomplete combustion of these alkanes and the trend in the energy changes they produced.

You should give word equations in your answer.

Figure 14 shows the structure of a molecule of hydrocarbon Z, C₄H₈.

Give the name of hydrocarbon Z shown in Figure 14.

Complete the balanced equation for the reaction of hydrocarbon Z, C₄H₈, with bromine.

Draw the repeating unit of the addition polymer formed when hydrocarbon Z undergoes polymerisation.

Figure 15 shows the arrangement of atoms in a molecule of an alcohol.

Give the name of the carbon‑containing product formed when the alcohol in Figure 15 undergoes dehydration.

Give the formula of the functional group of the product formed when the alcohol in Figure 15 undergoes oxidation.

A student wants to investigate the amount of energy released when 1.00 g of the alcohol is burned.

They set up the apparatus shown in Figure 16 to measure the temperature rise of the water.

State why this apparatus is not suitable for use in this experiment.

Some alcohols can react with some carboxylic acids to form polyesters, which are condensation polymers.

Figure 17 shows the repeating unit of the polyester molecule formed in a reaction between a carboxylic acid and an alcohol.

Give the formula of the other product formed in this reaction.

Draw the structure of one molecule of the alcohol used to produce the polyester shown in Figure 17, showing all covalent bonds.

This question is about polymers.

State a problem with recycling polymers.

Describe a problem associated with the disposal of polymers.

Poly(chloroethene) is a polymer made from chloroethene. A molecule of chloroethene is shown in Figure 20.

On Figure 20, draw a circle around the functional group in this molecule.

Draw a section of a poly(chloroethene) molecule containing three repeating units, showing all bonds.

What type of polymer is poly(chloroethene)?

Calculate the relative formula mass of a poly(chloroethene) molecule made from 2850 chloroethene molecules, C₂H₃Cl.

(relative atomic masses: H = 1.00, C = 12.0, C l = 35.5)

Give your answer to three significant figures.

Show your working.

relative formula mass =_........

This question is about polymers.

State a problem with recycling polymers.

Describe a problem associated with the disposal of polymers.

Poly(chloroethene) is a polymer made from chloroethene. A molecule of chloroethene is shown in Figure 5.

On Figure 5, draw a circle around the functional group in this molecule.

Draw a section of a poly(chloroethene) molecule containing three repeating units, showing all bonds.

What type of polymer is poly(chloroethene)?

Calculate the relative formula mass of a poly(chloroethene) molecule made from 2850 chloroethene molecules, C₂H₃Cl.

(relative atomic masses: H = 1.00, C = 12.0, C l = 35.5)

Give your answer to three significant figures.

Show your working.

relative formula mass =_........

Propanol, C₃H₇OH, can undergo reactions to form compounds Y and Z shown in Figure 14.

Figure 14

What happens to propanol when it forms compound Y ?

Compound Y can also be formed in the following reaction

C H C H

Explain how bromine water can be used to distinguish between compound X and compound Y.

Compound Z is a carboxylic acid.

Which of the following shows the functional group of a carboxylic acid?

Compound Z is an acid and turns litmus and universal indicator papers red. Compound Z also shows other acidic properties.

Devise an experiment that would show another acidic property of compound Z.

The balanced equation for the production of ethanol from the carbohydrate sucrose is

sucrose

Calculate the minimum mass of sucrose needed to produce 26.9 g of ethanol.

(relative formula masses: C₂H₅OH = 46, C₁₂H₂₂O₁₁ = 342)

minimum mass of sucrose =_........

Calculate the total number of atoms in 10.0 g of sucrose, C₁₂H₂₂O₁₁.

(relative formula mass: C₁₂H₂₂O₁₁ = 342; Avogadro constant = 6.02 × 10²³)

number of atoms =_........

Figure 16 shows the structure of a molecule of dichloroethene.

Describe how dichloroethene monomers form a polymer.

Separate samples of dichloroethene and poly(dichloroethene) are shaken with a few drops of bromine water.

What would be seen ?

Dichloroethene is produced from ethene and chlorine.

In the overall reaction, ethene reacts with chlorine and forms dichloroethene and hydrogen chloride.

Complete the balanced equation for the overall reaction.

Poly(dichloroethene) was used to wrap food to keep it fresh.

Explain one property that a plastic food wrapping must have.

An industrial process uses 500 tonnes of dichloroethene. In the process only 96.5% of the dichloroethene molecules react.

Calculate the mass of dichloroethene that has not reacted.

Give your answer to two significant figures.

Figure 2 shows the structure of a molecule of dichloroethene.

Describe how dichloroethene monomers form a polymer.

Separate samples of dichloroethene and poly(dichloroethene) are shaken with a few drops of bromine water.

What would be seen ?

Dichloroethene is produced from ethene and chlorine.

In the overall reaction, ethene reacts with chlorine and forms dichloroethene and hydrogen chloride.

Complete the balanced equation for the overall reaction.

Poly(dichloroethene) was used to wrap food to keep it fresh.

Explain one property that a plastic food wrapping must have.

An industrial process uses 500 tonnes of dichloroethene. In the process only 96.5% of the dichloroethene molecules react.

Calculate the mass of dichloroethene that has not reacted.

Give your answer to two significant figures.

Propene can be produced by the cracking of some hydrocarbons obtained from crude oil.

The equation shows the cracking of one molecule of decane to produce one molecule of butene and one molecule of another product.

decane butene

Calculate the values of x and y in C_xH_y.

State the total mass of products formed if 25 g of decane is cracked in this way.

The structure of a molecule of ethene is shown in Figure 8.

Figure 9 shows the incomplete dot and cross diagram for a molecule of ethene.

Complete Figure 9 to show the electrons of the C C double bond.

The incomplete combustion of ethene in air produces water as one of the products.

Give the name of another product of the incomplete combustion of ethene.

Substance X is an unsaturated hydrocarbon. The structure of a molecule of substance X is shown in Figure 10.

Explain how the structure of substance X shows that it is an unsaturated hydrocarbon.

Two liquid hydrocarbons, A and B, were tested with bromine water. One hydrocarbon was known to be an alkane. The other hydrocarbon was known to be an alkene.

Each hydrocarbon was shaken with a few drops of bromine water.

The results of the tests were hydrocarbon A + bromine water: the mixture turned from orange to colourless. hydrocarbon B + bromine water: the orange colour remained.

Explain these results.

Ethene, C₂H₄, is an unsaturated hydrocarbon.

Explain why ethene is an unsaturated hydrocarbon.

A sample of ethene is burned completely in oxygen.

Write the balanced equation for this reaction.

Ethene can be polymerised to form poly(ethene).

Describe what you would see when a sample of ethene and a sample of poly(ethene) are shaken with separate, small volumes of bromine water.

A different hydrocarbon has a relative formula mass of 84. It has an empirical formula of CH₂.

Deduce the molecular formula of this hydrocarbon.

You must show your working.

(relative atomic masses: H=1, C=12)

(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.