Find the ΔE of the combustion of octane in a bomb calorimeter

AI Thread Summary
The discussion focuses on calculating the ΔE for the combustion of octane in a bomb calorimeter using the provided data. The user calculated the heat absorbed by water as 236.8 kJ and the heat from the calorimeter as 37.13 kJ, totaling 273.9 kJ. However, upon dividing this total by the moles of octane, the user obtained -5494.25 kJ/mol, which differs from the expected -5506.3 kJ/mol. A question arises regarding the textbook's instruction to use only the calorimeter's heat for ΔE calculations, prompting a clarification on the appropriate method. The discussion emphasizes the importance of correctly applying thermodynamic principles in calorimetry.
MarcL
Messages
170
Reaction score
2

Homework Statement



Consider the combustion of octane that is burned in a bomb calorimter in the presence of 10.00kg of water. When burning 8.10mL of octane (.703g/ml=d) the temp. of the surrounding water increase by 5.66°C. The heat capacity of the bomb calorimter is 6.656Kj/ °C and the water is 4.184 j/g x °C

Homework Equations



q=mcΔT
qcal=Ccal x ΔT
ΔErxn= qrxn / moles of octane

The Attempt at a Solution



find Q of water which gave me 236.8 KJ by q=mcΔT ( m = 10000KG )
and find Q cal which ended up to 37.13 KJ by q=Ccal ΔT
then I added both Heat to get 273.9 Kj and then I divided by the number of mole found which was .049852045 moles.

However I got as an answer -5494.25 and the answer is -5506.3 Kj/mol

P.s: why does my textbook says to just use the Q of the calorimter and not add it up to the one of water in order to find the ΔE?
 
Physics news on Phys.org
Check your arithmetic.
 
Thread 'Confusion regarding a chemical kinetics problem'

Thread 'Confusion regarding a chemical kinetics problem'

TL;DR Summary: cannot find out error in solution proposed. [![question with rate laws][1]][1] Now the rate law for the reaction (i.e reaction rate) can be written as: $$ R= k[N_2O_5] $$ my main question is, WHAT is this reaction equal to? what I mean here is, whether $$k[N_2O_5]= -d[N_2O_5]/dt$$ or is it $$k[N_2O_5]= -1/2 \frac{d}{dt} [N_2O_5] $$ ? The latter seems to be more apt, as the reaction rate must be -1/2 (disappearance rate of N2O5), which adheres to the stoichiometry of the...
View full post »

Thread 'Prove that evolution is constant (Provide at least two arguments to support your position)'

I don't get how to argue it. i can prove: evolution is the ability to adapt, whether it's progression or regression from some point of view, so if evolution is not constant then animal generations couldn`t stay alive for a big amount of time because when climate is changing this generations die. but they dont. so evolution is constant. but its not an argument, right? how to fing arguments when i only prove it.. analytically, i guess it called that (this is indirectly related to biology, im...
View full post »

Similar threads

Calculating Heat Capacity in a Bomb Calorimeter using Combustion of Toluene
Replies
5
Views
4K
How Do You Calculate Combustion Energy in Bomb Calorimetry?
Replies
3
Views
2K
Heat of Combustion of N2H4 - Calculating Final Temperature
Replies
10
Views
4K
Calculate the molar heat of combustion of anthracene
Replies
3
Views
6K
Work done by Octane Combustion Engine
Replies
2
Views
2K
Enthelpy Change of Combustion.
Replies
1
Views
5K
Heat Capacity of Bomb Calorimeter: Questions & Answers
Replies
5
Views
18K
Calculate Temp Increase for Enthalpy of Sulfur Burning in Excess O2
Replies
1
Views
3K
Help with enthelpy change and Hess's Law
Replies
1
Views
4K
Why is this calculation of the enthelpy of combustion wrong?
Replies
4
Views
2K

Hot Threads

Recent Insights

Back
Top