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hikerjo
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hikerjo
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PostMon Apr 28, 2003 8:05 pm 
Is there anyone out there that can explain to me how to do this problem and what the answer is? 3% H2O2 decomposes into O2 + H20 in a calorimeter. If 47.6 ml of this soulution increases the temp from 20.0 to 35.0 degrees celsius determine the deltaH/mol of this reactant as measured by the experiment. Any ideas?

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Tom
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PostMon Apr 28, 2003 8:18 pm 
How many hats is it worth to you? tongue.gif

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hikerjo
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PostTue Apr 29, 2003 4:04 pm 
embarassedlaugh.gif

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hikerjo
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PostTue Apr 29, 2003 4:05 pm 
I dont have any hats! I decided to get maps instead wink.gif .

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polarbear
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PostTue Apr 29, 2003 7:04 pm 
Quote:
3% H2O2 decomposes into O2 + H20 in a calorimeter. If 47.6 ml of this soulution increases the temp from 20.0 to 35.0 degrees celsius determine the deltaH/mol of this reactant as measured by the experiment. Any ideas?
You need to find out how many moles there are. Do you know the molarity of the solution (like is there a table somewhere in the middle of the chapter)? moles = molarity X liters maybe the 3% has to be factored in. Is delta H just 15 deg. C? I haven't taken chemistry since high school and I was in the slow class there. Take any of my advice with one eye closed wink.gif and verify the answer with that in the back of the book.
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hikerjo
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PostTue Apr 29, 2003 7:24 pm 
I used to know how to do this, then took a test the other day and coulnt remember. This was the question on my test so there is no infomration on it in the book. I know you need to get the energy in Joules, by using Q+SMdeltaH, which is easy and you need to get the moles, which is easy. I just dont know what to do next! shakehead.gif

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mb
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PostTue Apr 29, 2003 10:08 pm 
Well if Δh is 15 degrees, and the molarity is (uh, however many moles there are in 3% of H2O2. and is the reactant the entire solution (47.6 l) or just the peroxide?), then just divide. Almost everything in chemistry can be done my making sure the units match up, or so my high school chem teacher said. Works in many other disciplines too.

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Rich Baldwin
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PostTue Apr 29, 2003 10:54 pm 
Look in the back of your chemistry book for the standard molar enthalpy of formation for the products and reactants.

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