Formulae, Functional Groups & Terminology (CIE IGCSE Chemistry: Co-ordinated Sciences (Double Award))

The alkanes are a homologous series of hydrocarbons which are used as fuels. Their general formula is C_nH_2n+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.

Draw a line of best fit on the grid.

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

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

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

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.

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.