how many nutritional Calories are there per gram of the candy?

Question

A researcher studying the nutritional value of a new candy places a 6.60 g sample of the candy inside a bomb calorimeter and combusts it in excess oxygen. The observed temperature increase is 2.88 ∘C. If the heat capacity of the calorimeter is 45.80 kJ⋅K−1, how many nutritional Calories are there per gram of the candy?

Calories per gram of candy: ?Cal/g

Answer 1

q = C∆T

q = heat = ?

C = calorimeter constant (heat capacity) = 45.80 kJ/º (note: K or C temperature scale doesn't matter)

∆T = change in temperature = 2.88º

q = (45.80 kJ/º)(2.88º) = 131.90 kJ

On a per gram basis, this is 131.90 kJ / 6.60 g = 19.98 kJ

The question asks for the answer in Calories (nutritional calories) so we convert kJ to Calories as follows:

19.98 kJ x 1 Cal / 4.184 kJ = 4.78 Cal/g (3 sig.figs.)