[joeypagliarulo11]

Please help me with these problems, I have no idea where to start.

(1) The following substances undergo complete combustion in a bomb calorimeter. The bomb calorimeter assembly (including the water) has a heat capacity of 4.1881 KJ/degrees C. In each case, what is the final water temperature if the initial water temperature is 24.62 degrees C.
a. 0.5187 grams of cyclohexane (C6H12O(I));
heat of combustion = -3727 kJ/mol

b. 1.72 mL of ethyl acetate (C4H8O2(I), density = 0.901 g/mL);
heat of combustion = -2246 kJ/mol.

(2) A 0.50 gram sample of NH4NO3 is added to 35.0 grams of water in a "coffee cup" (constant pressure) calorimeter and stirred until it dissolves. The temperature of the solution drops from 22.7 degrees C to 21.6 degrees C. What is the HEAT OF SOLUTION of NH4NO3 expressed in KJ/mol NH4NO3.

[Borek]

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[consul]

Ok. Here is an idea for you:
For question number 1 (both a and b).
From the chemical formula of cyclohexane, can you get the MW? (yes/no? Use your periodic table). Now you have the value in grams/mol. Correct? From the given mass of cyclohexane can you get the mols of cyclohexane? (How? I suppose you know how to convert using the MW).
You have now the mols of cyclohexane. From the heat of combustion of cyclohexane in kJ/mol, can you get the KJ of heat? (How? Heat of combustion becomes a conversion factor!)
Now, you have the KJ of heat. Since you are looking for a heat of combustion it means that the reaction (absorbs or releases heat?). Ok does the calorimeter (absorb or release heat?). 
Set up the equation

   Heat released by ________ = heat absorbed by _________
         kJ  = kJ
   From the equation above you get the heat absorbed by the calorimeter.
   Heat absorbed by calorimeter = Heat capacity x delta T
   You have the initial temperature of water which is also the initial temperature of _______.
 You know what the deltaT is? (Right? So you can get the final temperature).
                 
For number 2:
The water (absorbs or releases? ) heat.
This heat comes from the heat of solution of ethyl acetate.
Specific heat of water is _______ ?
From the specific heat of water, its ____, and deltaT you get your heat.
H= ___ x cp x deltaT.

The heat to/from water is the heat of solution. The unit required is KJ/mol.
Convert the given grams of ethyl acetate to mol. (I think you know how).
From there, what should you do to the heat that you solved to get kJ/mol?

That's it!

Good luck.

I hope I have given the right direction. Next time solve more examples to learn.

Please help me with these problems, I have no idea where to start.

(1) The following substances undergo complete combustion in a bomb calorimeter. The bomb calorimeter assembly (including the water) has a heat capacity of 4.1881 KJ/degrees C. In each case, what is the final water temperature if the initial water temperature is 24.62 degrees C.
a. 0.5187 grams of cyclohexane (C6H12O(I));
heat of combustion = -3727 kJ/mol

b. 1.72 mL of ethyl acetate (C4H8O2(I), density = 0.901 g/mL);
heat of combustion = -2246 kJ/mol.

(2) A 0.50 gram sample of NH4NO3 is added to 35.0 grams of water in a "coffee cup" (constant pressure) calorimeter and stirred until it dissolves. The temperature of the solution drops from 22.7 degrees C to 21.6 degrees C. What is the HEAT OF SOLUTION of NH4NO3 expressed in KJ/mol NH4NO3.