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The enthalpies of combustion of four alcohols were determined in a school laboratory - HSC - SSCE Chemistry - Question 29 - 2022 - Paper 1
Question 29
The enthalpies of combustion of four alcohols were determined in a school laboratory. The results are shown in the table. | Alcohol | ΔH (kJ mol⁻¹) | |-----... show full transcript
Worked Solution & Example Answer:The enthalpies of combustion of four alcohols were determined in a school laboratory - HSC - SSCE Chemistry - Question 29 - 2022 - Paper 1
Step 1
Plot the results on the graph
Answer
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First, create a table with the number of carbon atoms in the alcohols (1 to 5) and their corresponding enthalpy values:
Number of Carbons ΔH (kJ mol⁻¹) 1 –596 2 –978 3 –1507 4 ? 5 –2910 -
Plot each point on the graph based on the above values. For example, plot (1, -596), (2, -978), (3, -1507), and (5, -2910).
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Draw a smooth curve of best fit through the points.
Step 2
Estimate the enthalpy of combustion of butan-1-ol
Answer
Using the graph, extend the curve to find the point where it corresponds to 4 carbon atoms. Estimate the value of ΔH at this point by reading off the graph. The estimated enthalpy of combustion of butan-1-ol is approximately –2100 kJ mol⁻¹.