Calories...Help!

Question

A researcher studying the nutritional value of a new candy places a 3.40 gram sample of the candy inside a bomb calorimeter and combusts it in excess oxygen. The observed temperature increase is 2.36 C. If the heat capacity of the calorimeter is 46.80 kJ*K^-1, how many nutritional calories are there per gram of the candy?

Answer 1

Heat released=heat capacity*change in temperature

#calories=#joules*(1 calorie/4.184 J)

 

a) convert heat capacity to joules per Kelvin (multiply Heat capacity by 1000 J/kJ)

b) determine heat released by multiplying heat capacity by change in temperature (2.36 C is equivalent to 2.36 K)

c) determine calories by multiplying value of joules by (1 cal/4.184 J)

d) determine calories per gram by dividing value of calories by mass of candy (3.40 grams)

 

1) heat released (in calories)=

46.80 kJ/K * 1000 J/kJ  or 46, 800 J/K

46,800 J/K * 2.36 K or 110, 448 J

110, 448 J * (1 cal/4.184 J) or 26, 398 cal

 

2) # calories per gram=26, 398 calories/3.40 grams or 7, 764 calories/gram