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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: dirknathan on October 11, 2012, 03:47:03 PM

Title: Calorimeter problem. (Halloween theme!)
Post by: dirknathan on October 11, 2012, 03:47:03 PM
When 1.0 gram of candy bar was placed in a bomb calorimeter and ignited, the temperature rose from 23.8 °C to 42.9 °C.  If the heat capacity of the calorimeter is 1023 J/°C (which includes the contribution from the water jacket).

a)Calculate the energy released per gram of candy bar in terms of kJ.


b) If each Halloween snack-sized candy bar is 15 g, how many Calories are consumed once you polish off a handful (6 candy bars) of Trick-or-Treating loot? (1 Calorie = 1 kcal)



Now, I have no idea how to even approach this.  All my notes include the mass of water in the calorimeter.
Title: Re: Calorimeter problem. (Halloween theme!)
Post by: Borek on October 11, 2012, 04:42:00 PM
Heat capacity of water (mc) is already included in the heat capacity of the calorimeter.
Title: Re: Calorimeter problem. (Halloween theme!)
Post by: dirknathan on October 12, 2012, 12:57:36 AM
ΔH = mcΔT?
Title: Re: Calorimeter problem. (Halloween theme!)
Post by: Borek on October 12, 2012, 03:16:44 AM
ΔH = mcΔT?

Yes, just instead of mc you use one value of a total heat capacity of calorimeter.
Title: Re: Calorimeter problem. (Halloween theme!)
Post by: curiouscat on October 12, 2012, 03:22:29 AM
When 1.0 gram of candy bar was placed in a bomb calorimeter and ignited

How'd one ignite a candy bar?  ???

Especially without altering the heat of reaction a lot and at 28 C..
Title: Re: Calorimeter problem. (Halloween theme!)
Post by: dirknathan on October 12, 2012, 11:37:16 AM
Idk buddy!  Haha. Could someone please how me the process of filling in the formula?  I'm not trying to get I freebie.  I need to understand it.  The process of filling the formula with the proper units will be great!  I can do the calculations, obviously.
Title: Re: Calorimeter problem. (Halloween theme!)
Post by: Borek on October 12, 2012, 02:49:05 PM
First try by yourself, you will learn more this way. And don't be afraid of being wrong - the only people that never do any mistakes are those that never do anything.
Title: Re: Calorimeter problem. (Halloween theme!)
Post by: dirknathan on October 15, 2012, 11:51:19 PM
I already have.  I got the wrong answer.
Title: Re: Calorimeter problem. (Halloween theme!)
Post by: Borek on October 16, 2012, 03:36:53 AM
Then show what you did and we will start from there.