July 04, 2022, 12:05:21 PM
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Topic: Having trouble with thermochemistry problem (specific heat etc) please help  (Read 5960 times)

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kb18

  • Guest
I don't know how to solve these problem, I've looked at numerous equations and don't know how to set it up, please help. My teacher is horrible, she refuses to help me....

1.) A piece of a newly synthesized material of mass 25.0 g at 80.0 degrees celcius is placed in a calorimeter containing 100.0 g of water at 20.0 degrees celcius.

If the final temperature of the system is 24.0 degree celcius, what is the specific heat capacity of this material?



2. How much heat is absorbed in the complete reaction of 3.00 grams of SiO2 with excess carbon in the reaction below
    Sio2(g)+3C0s)---->SiC(s)+2CO(g)

Delta H for the reaction is +624.7kj/ mol rxn.



3. 4.6 g of a hydrocarbon fuel is burned in a calorimeter that contains 252 grams of water initially at 25.00 degree celcius. Afte rthe combustion, the temperature is 26.55 degree celcius. How much heat is evolved per gram of fuel burned? The heat capacity of the calorimeter is 92.3 J/degrees celcius
« Last Edit: March 31, 2006, 11:51:37 AM by kb18 »

dmitriy

  • Guest
If I am not mistaken by law of conservation of energy the energy of materal was spent to heat water
Energy is expressed as Cmat*m(mat)*deltaT=Cwater*m(water)*deltaT
first delta t is 80-56
second delta t is 24-20
Specific heat for water is 4200 j/kg*K
From here you can derive Cmat

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