A researcher studying the nutritional value of a new candy places a 6.60 g 6.60 g sample of the candy inside a bomb calorimeter and combusts it in excess oxygen. The observed temperature increase is 2.46 ∘ C. 2.46 ∘C. If the heat capacity of the calorimeter is 33.90 kJ ⋅ K - 1, 33.90 kJ⋅K-1, how many nutritional Calories are there per gram of the candy?

Question

Physics

Adrienne Holland

21 May, 09:15

A researcher studying the nutritional value of a new candy places a 6.60 g 6.60 g sample of the candy inside a bomb calorimeter and combusts it in excess oxygen. The observed temperature increase is 2.46 ∘ C. 2.46 ∘C. If the heat capacity of the calorimeter is 33.90 kJ ⋅ K - 1, 33.90 kJ⋅K-1, how many nutritional Calories are there per gram of the candy?

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Answers (1)

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Lawrence Bernard · Answer 1

there are 3.018 kcal = 3018 cal per gram of candy

Explanation:

If the assume that the calorimeter is perfectly insulated, then all the heat released by the combustion is absorbed by the calorimeter.

Also knowing that Q = C * ΔT, where C = heat capacity of the calorimeter, ΔT = temperature change, Q = heat released by the combustion of the candy

replacing values

Q = C * ΔT = 33.90 kJ/°C * 2.46°C = 83.394 kJ

since Q is the heat released when burned all the mass m of the candy, the number of calories per gram of candy will be

q = Q/m = 83.394 kJ / 6.60 g = 12.635 kJ/g

q = 12.635 kJ/g * 1 kcal / 4.186 kJ = 3.018 kcal per gram of candy