CIE IGCSE Chemistry

Topic Questions

11.1 Formulae, Functional Groups & Terminology

1a1 mark

The alkanes are a homologous series of hydrocarbons which are used as fuels. Their general formula is CnH2n+2.

The energy released when equal amounts of the first five alkanes were burned was measured. The results are shown plotted on the grid below.

XD3Y41lP_alkane-combustion-homologous-series-graph

Draw a line of best fit on the grid.

1b2 marks

Suggest two reasons why not all of the points lie on the line of best fit.

1 ....................................................................................................

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

1c2 marks

Use your graph to work out the amount of energy released when the same amount of hexane, C6H14, is burned. Show clearly how you worked out your answer.

1d3 marks

A student predicted that the energy released by burning butane would be two times the energy produced by burning ethane.

Suggest why she made this prediction and compare the values obtained for these two alkanes.

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