How many nutritional calories are there per gram of candy?

Question

A researcher studying the nutritional value of a new candy place is a 4.2 g sample of the candy inside a bomb calorimeter and combusts it in excess oxygen. The observed temperature increases is 2.69°C. If the heated capacity of the Cala meter is 34.60KJ.K -1, how many nutritional calories are there program in the candy?

Answer 1

For a bomb calorimeter, we can use the following expression:

q = Ccal x ∆T

q = heat = ?

Ccal = calorimeter capacity 34.60 kJ/degree

∆T = change in temperature = 2.69º

Solving for q, we have ...

q = 34.60 kJ / degree x 2.69 degrees = 93.07 kJ of heat energy

The question asks for nutritional calories per gram of candy, so first we'll express our answer in nutritional calories, and then divide that by the 4.2 g of candy. Note that 4.184 kJ = 1 kcal and 1 kcal = 1 nutritional Calorie.

93.07 kJ x 1kcal / 4.184 kJ = 22.24 kcal

22.24 kcal x 1 Cal / kcal = 22.24 Cal = 22.24 nutritional calories

22.24 nutritional calories / 4.2 g = 5.3 nutritional calories / gram of candy