Help with Thermochemistry Question

[pnoybballin]

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What is the energy content in kcal of one hazelnut, if the temperature of 0.5 kg of water in a calorimeter increases by 30 degrees C upon burning 5 hazelnuts?

A. 3 kcal
B. 12 kcal
C. 15 kcal
D. 60 kcal

The answer is A. Could someone please help explain this problem?

 

[musafirah]

the energy in the hazelnuts is related as the heat transfer to .5 kilo of water needed to raise the temperature of water 30C.

Q= mcT
Q is the energy your looking for. specific heat of water, c= 1 kcal/kg
Temp change T = 30K
mass of water is m= .5 kg

Q = .5 (1) (30)

Q total = 15 kcal

this is the energy burned for 5 hazelnuts. the question says for 1 hazelnut, so just divide Q total by 5, and you get 3 kcal per hazelnut

 

[pnoybballin]

Oh man, wasn't that bad. Thanks a lot.