A student performed an experiment to compare the energy content of dry broad beans and dry soybeans - VCE - SSCE Chemistry - Question 8 - 2023 - Paper 1

The temperature change of the water should be recorded throughout the experiment. Specifically, the final temperature of the water after the combustion of the dry broad-bean powder needs to be noted.

Safety precautions such as using a heatproof mat and allowing the water to cool below 30 °C are essential to prevent risk of fire or burns. The heatproof mat mitigates the risk of the laboratory catching fire, while cooling the water reduces the chance of scalding.

Using the formula for energy change: $q = mcΔT$ where:

• m = mass of the water (300.0 mL, equivalent to 300.0 g),
• c = specific heat capacity of water (4.18 J/g°C),
• ΔT = change in temperature.

Assuming a temperature change from 25 °C to the final recorded temperature, energy change calculation will provide the total energy absorbed by water.

From the data collected, the energy content can be calculated. For example, if the energy change calculated was 1816 kJ for 100 g, the final energy content can be stated as: Energy content per 100 g = 1816 kJ.

An improvement could be to ensure better insulation around the setup. This would minimize heat loss to the environment which can affect the final temperature readings and ensure a more accurate measurement of the energy content of the beans.

The energy content measured for the soybeans versus broad beans can be compared. Typically, more energy is expected from beans higher in fat and protein content, indicating variations in their nutritional profiles and potential energy yield.