A student carries out a simple calorimetry experiment to determine the energy content of a dry sunflower seed.
They burn a single sunflower seed of mass 0.50 g under a boiling tube containing 20.0 g of water. The temperature of the water of mass 20.0 g rises from an initial temperature of 18.5∘C18.5^\circ\text{C}18.5∘C to a maximum temperature of 41.5∘C41.5^\circ\text{C}41.5∘C.
If the specific heat capacity of water is 4.2 J g−1 ∘C−14.2\text{ J g}^{-1}\text{ }^\circ\text{C}^{-1}4.2 J g−1 ∘C−1, calculate the heat energy released to the water by the burning seed in Joules (J\text{J}J).
Calculate the energy content of the seed per gram of its mass in kJ g−1\text{kJ g}^{-1}kJ g−1.
Suggest why the calculated energy content is likely to be lower than the actual energy stored in the seed, and state two practical improvements to the experimental setup to minimize this difference.
Name the main type of food molecule stored in sunflower seeds, and explain why it is essential for the seed to have a food store during the initial stages of germination.
