A student investigates the temperature rise produced when different alcohols are burned.
The student puts 100 cm3\mathrm{cm^{3}}cm3 of water in a copper can clamped above a spirit burner. The student burns each alcohol until the water has been heated for 3 minutes, then measures the mass of alcohol burned and the temperature of the water.
The table shows the results.
| Alcohol | Mass of alcohol burned / g | Starting temperature / °C | Final temperature / °C | Temperature rise per gram / °C per g |
|---|---|---|---|---|
| ethanol | 1.20 | 20.0 | 44.0 | 20.0 |
| propanol | 1.00 | 20.5 | 45.5 | 25.0 |
| butanol | 0.80 | 21.0 | 43.4 | ? |
| pentanol | 0.75 | 20.0 | 42.5 | 30.0 |
Give the independent variable in this investigation.
Give two variables the student should control.
Calculate the temperature rise of the water for butanol.
Calculate the temperature rise per gram for butanol. Use the equation: temperature rise per gram=temperature risemass of alcohol burned\displaystyle \text{temperature rise per gram} = \frac{\text{temperature rise}}{\text{mass of alcohol burned}}temperature rise per gram=mass of alcohol burnedtemperature rise
Describe the relationship between the number of carbon atoms in the alcohol and the temperature rise per gram.
Much of the energy released by the burning alcohol does not heat the water. Suggest one improvement to the apparatus to reduce this energy loss.
43 exam-style questions on Edexcel GCSE Chemistry 10.4 Alcohols and carboxylic acids, covering 10.4.1 Alcohols and the -OH functional group, 10.4.2 Carboxylic acids and the -COOH functional group, 10.4.3 Oxidation of alcohols and homologous series, and 10.4.4 Fermentation and fractional distillation of ethanol. Each one has a worked solution and a mark scheme showing where the marks go.