Calculating Calorimeter Heat Capacity for Naphthalene Combustion

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Homework Help Overview

The discussion revolves around calculating the heat capacity of a calorimeter used in the combustion of naphthalene. The original poster presents a scenario involving the combustion of 136.8 mg of naphthalene, leading to a temperature change in the calorimeter.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate the calorimeter heat capacity using the heat of combustion and the temperature change but expresses uncertainty about the values used for delta H and the entropy of naphthalene. Other participants suggest equating the heat of combustion to the heat gained by the calorimeter.

Discussion Status

Participants are actively exploring different approaches to the problem, with some expressing frustration over the calculations. The original poster is seeking clarification on the values used and has indicated plans to consult a lecturer for further assistance.

Contextual Notes

There is mention of specific values for the heat of combustion and the molar mass of naphthalene, as well as a temperature change observed in the calorimeter. The original poster also questions the accuracy of the entropy value they found online.

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You burn 136.8 mg of naphthalene in a calorimeter and the temperature of the calorimeter rises by 3.29 oC. Determine the calorimeter heat capacity in J K-1. The molar mass of naphthalene is 128.18 g mol-1

This is a question from a quiz I have to do.
this is wat I did.
Ccal=delta H/delta n=0.1368g/128.18g/mol
=1.06E-3moles

I don't know how to calc delta H from this info but I looked it up on the net and found 72.6+0.6kJ/mol.
Thats not right is it coz when I put this information in the formula
Ccal=((72.6+0.6)x1000j/molx1.06E-3)/(3.29+273.15)

I got it wrong... any help?
Does anyone know if my value for entropy of napthalene is right?
 
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Taryn said:
You burn 136.8 mg of naphthalene in a calorimeter and the temperature of the calorimeter rises by 3.29 oC. Determine the calorimeter heat capacity in J K-1. The molar mass of naphthalene is 128.18 g mol-1

This is a question from a quiz I have to do.
this is wat I did.
Ccal=delta H/delta n=0.1368g/128.18g/mol
=1.06E-3moles

I don't know how to calc delta H from this info but I looked it up on the net and found 72.6+0.6kJ/mol.
Thats not right is it coz when I put this information in the formula
Ccal=((72.6+0.6)x1000j/molx1.06E-3)/(3.29+273.15)

I got it wrong... any help?
Does anyone know if my value for entropy of napthalene is right?

heat of combustion of naphthelene=5156 kJ/mole. I think u may equate this to heat gained by calorimeter.
 
Thanks I will try that!
 
Yeah I just tried to use that and still got it wrong its so frustrating! I will go and see my lecturer now and hopefully he can help. Can u see anything wrong with my process?
 

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