a. Exactly 4.000 mol of NH3 is burned in a constant volume (bomb) calorimeter immersed into 100.0kg of water. The temperature of water increases by 3.619 degrees C after the reaction. Calculate the heat released by the reaction. Neglect the heat capacity of the bomb and the calorimeter; assume that all the heat is spent on warming up water. Specific heat capacity for water is Cm= 4.184 J/ (gx°C)

Question

b. Explain why the absolute values of the standard enthalpy change in the reaction and the heat measured by the calorimeter are not equal. Assume that there are no measurement errors of any kind.

My work:

a.
qcal= C cal* dlta T
qcal= 4.184 * 3.619 = 15.142

This answer is wrong.

b. I don't have any idea on this part of the question

Can someone explain how to do this problem. Thanks!

Answer 1

You didn't count the water. The problem tells you to neglect the calorimeter so
q = mass H2O (100,000g) x specific heat H2O x delta T. I don't know what part b is talking about.

Answer 2

Is delta T (3.619-0)?????

Answer 3

yes

Answer 4

Yay! Okay thanks so much! :)