Questions

Q1.

A teacher explained the different types of formula used in organic chemistry, using ethene as an example.

(a) Use this example to help you write the formulae described below.

(i) The empirical formula of methane(1)

      ..............................................................................................................................................

(ii) The molecular formula of ethane(1)

      ..............................................................................................................................................

(iii) The structural formula of propane(1)

      ..............................................................................................................................................

(iv) The displayed formula of butane(1)

(b) All the compounds in part (a) belong to the same homologous series and have thesame general formula.

(i) State the name of this homologous series.(1)

      ..............................................................................................................................................

(ii) State the general formula of this homologous series.(1)

      ..............................................................................................................................................

(iii) State two characteristics of the compounds in a homologous series, other thanhaving the same general formula.

(2)1

      ..............................................................................................................................................      ..............................................................................................................................................

2      ..............................................................................................................................................      ..............................................................................................................................................

(c) All the compounds in part (a) are hydrocarbons. They can undergo completecombustion when burned in oxygen to form carbon dioxide and water.

(i) Write a chemical equation for the complete combustion of propane (C3H8).(2)

      ..............................................................................................................................................

(ii) Identify one solid product and one gaseous product that could form during theincomplete combustion of propane.

(2)Solid product

      ..............................................................................................................................................Gaseous product

      ..............................................................................................................................................

(d) The displayed formula of pentane is

Draw a displayed formula for each of the two isomers of pentane.(2)

(e) When methane reacts with bromine, one of the products is hydrogen bromide.(i) State a condition needed for this reaction.

(1)      ..............................................................................................................................................

(ii) Name the organic product of the reaction.(1)

      ..............................................................................................................................................

(iii) Write a chemical equation for the reaction.(2)

      ..............................................................................................................................................

(Total for question = 18 marks)

Q2.

Ethane (C2H6) is used as a starting material to manufacture addition polymers. It is first cracked to form ethene (C2H4).

(a)   Identify the fuel that also forms in this reaction.

(1) .............................................................................................................................................

(b)   Ethane is described as saturated.

What feature of an ethane molecule is responsible for this description?(1)

.............................................................................................................................................

.............................................................................................................................................

(c)   Bromine water can be used to show that a hydrocarbon is ethene rather than ethane.

(i)   Complete the equation to show the displayed formula of the product of the reaction between ethene and bromine.

(1)

(ii)   Which is the correct statement about this test?(1)

       A    the colour of ethene is brown

       B    the product of the reaction is a white precipitate

       C    the product of the reaction is colourless

       D    the test involves a substitution reaction

(d)   Alkenes can be polymerised.

Part of the structure of poly(ethene) can be represented as

This structure shows the atoms coming from two molecules of ethene.Draw part of the structure of poly(propene) that shows the atoms coming from two molecules of propene (CH2=CH–CH3).

(2)

(e)   The repeat unit of another addition polymer can be represented as

Draw the structure of the monomer used to make this polymer.(1)

(f)   The disposal of most addition polymers is a problem because they do not biodegrade.

(i)   What is meant by the term biodegrade?(2)

.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................

(ii)   Identify the property that prevents addition polymers from easily biodegrading.(1)

.............................................................................................................................................

  (Total for question = 10 marks)

Q3.

Decane is a hydrocarbon found in crude oil.The diagram shows the structure of a decane molecule.

(a) (i) Explain why decane is described as a hydrocarbon.(2)

      ..............................................................................................................................................      ..............................................................................................................................................

(ii) Give the molecular formula for decane.(1)

      ..............................................................................................................................................

(b) Decane and ethene, C2H4, are produced during the cracking of eicosane, C20H42

Ethene is used to make poly(ethene).

(i) What is the name given to this type of polymerisation?(1)

      ..............................................................................................................................................

(ii) Use the diagram to state two changes that occur during the formation of poly(ethene).(2)

      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................

(c) Explain why cracking is an important process in the oil industry.(4)

      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................      ..............................................................................................................................................

(Total for Question = 10 marks)

Q4. 

The diagram shows the separation of crude oil into fractions.

(a)  What is the name of this method of separation?

(1).............................................................................................................................................

(b)  Complete the table by giving the correct fraction, A, B, C, D, E or F, for each description.

You may use each letter once, more than once or not at all.(3)

(c)  State the relationship between the number of carbon atoms per molecule and the boiling point of the fraction. (1).............................................................................................................................................

............................................................................................................................................. (Total for question = 5 marks)

Q5.

Fractional distillation and cracking are important steps in processing crude oil.(a) Place ticks ( ) in the columns to show which statements apply to each step.

You may place a tick in one column, in both columns or in neither column. The first one has been done for you.

(5)

 (Total for question = 5 marks)