Calorimetry problem

Question

A researcher studying the nutritional value of a new candy places a 3.00 g3.00 g sample of the candy inside a bomb calorimeter and combusts it in excess oxygen. The observed temperature increase is 2.04 ∘C.2.04 ∘C. If the heat capacity of the calorimeter is 46.80 kJ⋅K−1,46.80 kJ⋅K−1, how many nutritional Calories are there per gram of the candy?

Calories per gram of candy:

Cal/g

Answer 1

1 Cal = 1 kcal = 4.1868 kJ

Since the candy is burnt, the heat lost by the candy is equivalent to the heat absorbed by the calorimeter.

Therefore, we need to calculate the heat energy absorbed by the calorimeter.

Q = C_calorimeter × ΔT

= 46.80 kJ K^-1 × 2.04 K = 95.47 kJ

(Change in temperature in Celsius is equivalent to change in temp. in Kelvin)

The heat released by 3.00 g of candy is 95.47 kJ



Nutritional calories per gram = (95.47kJ / 4.1868 kJ) / 3.00 g = 7.60 kcal/g = 7.60 Cal/g

Answer: 7.60 Cal/g