A 2.75 g sample of the hydrocarbon acetone, CH3COCH3, is burned in a bomb calorimeter with 975 mL of water, initially at 23.50 degrees celsius. The bomb is constructed of 285.0 g of nickel metal having a specific heat capacity of Cp = 0.826 J/ g degrees C. The final temperature of the bomb and the water after the combustion process increases to 29.55 degrees celsius. calculate the following:

Question

(a)The heat flow at constant volume, qv for this combustion (in kJ/mol).

i know qv = delta E. and that delta E = q + w. but how do i find the work? i know work = force / distance. (i'm struggling because my book gives an example where the work is already given so it is not helpful at all.)

(b)The energy released per mole of acetone (in kj/mole).

(c)calculation (b) amounts to the heat of combustion per mole, delta h comb/mole for this compound. Balance the reaction for the complete combustion of acetone, find delta n and then find the value of delta H per mole of acetone (kJ/mole).

i don't know how to even start part (b).

thank you!

Answer 1

You know the delta T for the metal and the water.
heat=masswater*cw*deltaT +massnickel*cn*deltatT
b) use that heat, per mole of acetone consumed (convert grams to moles)
c) Use Hess'law.