Homework Help: Chemistry

Posted by Jason on Saturday, September 18, 2010 at 8:30pm.

A 0.25g sample of a pretzel is burned. The heat it gives of is used to heat 50.g of water from 18 to 42 degrees C. what is the caloric value of the pretzel in kcal/g?
Can someone walk me through step by step?

Chemistry - DrBob222, Saturday, September 18, 2010 at 9:00pm
I don't know if this is a nutrition course or not. Sometimes we don't know if a Cal is a kcal or not. I will assume the question deals with 1 cal = 4.184 J.

q = mass water x specific heat water x delta T.
q = 50 x 1 cal/g x (42-18) = 1,200 calories.
Then 1,200/0.25 = 4,800 calories = 4.8 kcal/g
Chemistry - kacey, Monday, September 27, 2010 at 5:38pm
write out the steps

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