Chemistry - Thermochemistry Question with Solution | TestHub
A slice of banana weighing 2.5 g was burnt in a bomb calorimeter and produced a temperature rise of 3.0 K. In the same calorimeter, combustion of a 0.305 g sample of benzoic acid produced a temperature rise of 4.0 K. The heat of combustion of benzoic acid at constant volume is -800 kcal/mol. If an average banana weighs 125 g, how many calories can be obtained from one average banana?
Answer:
Solution:
For benzoic acid, the heat released (q) is calculated as:
q = (800 × 0.305)/122 = 2.0 kcal
This heat corresponds to a temperature change of 4.0 K. Therefore, the heat capacity (C) is:
C = 2.0 kcal/4.0 K = 0.5 kcal/K
For the banana slice, the heat released (q) is:
q = 0.5 kcal/K × 3.0 K = 1.5 kcal for a 2.5 g sample.
This means the energy content per gram of banana is:
1.5 kcal/2.5 g = 0.6 kcal/g
For a 125 g banana, the total energy content is:
125 g × 0.6 kcal/g = 75 kcal (which is equivalent to 75 Calories).
Answer: 0075.
