4

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: . . . . . . . . . . ............................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . Disadvantage . ...................................................................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . (Total for Question 18 = 20 marks) *N37962A01924* 19 Turn over BLANK PAGE 20 *N37962A02024* 19 The enthalpy change of combustion of ethanol was determined using the apparatus shown in the diagram below. In the experiment, the temperature increase of the water in the beaker is measured when a known mass of the ethanol is burned. water beaker spirit burner (a) The results of the experiment are summarised in the table below. Mass of water in the beaker 250.00 g Mass of spirit burner + contents (initial) 63.21 g Mass of spirit burner + contents (final) 62.47 g Temperature of water (initial) 21.0 °C Temperature of water (final) 31.5 °C (i) Calculate the heat energy produced by the combustion of the alcohol using the equation heat energy produced (J) = mass of water × 4.18 × temperature change (1) *N37962A02124* 21 Turn over (ii) Calculate the number of moles of ethanol burned in this experiment (the formula of ethanol is C2H5OH). (3) (iii) Use the equation below to calculate the enthalpy change of combustion of ethanol in kJ mol–1. Give the value an appropriate sign. H = heat energy produced ÷ number of moles (2) (b) The data book value for the enthalpy change of combustion of ethanol is –1370 kJ mol–1. (i) Calculate the percentage error in the value calculated in (a)(iii) in comparison with the data book value. (1) 22 *N37962A02224* (ii) List three ways in which the design of the experiment causes the results to be so different from the data book value. (You should be specific but detailed explanations are not required.) (3) 1 . . . . . . .............................. .............................................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....
View Full Document

Ask a homework question - tutors are online