Converting Btu to J: Troubleshooting Heat Capacity of Water

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Homework Help Overview

The original poster attempts to convert British thermal units (Btu) to joules (J) using the heat capacity of water. The problem involves understanding the relationship between different units of temperature and mass in the context of heat capacity.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the conversion factors for temperature and mass, questioning the original poster's use of the Fahrenheit to Kelvin conversion. There are suggestions to reconsider the conversion factor for temperature and clarifications about the relationship between Fahrenheit and Celsius.

Discussion Status

Participants are actively engaging with the original poster's calculations, offering alternative perspectives on the conversion factors. There is no explicit consensus, but several lines of reasoning are being explored regarding the correct approach to the temperature conversion.

Contextual Notes

The discussion includes potential confusion regarding the conversion of temperature units and the specific heat capacity of water, as well as the implications of using different temperature scales in the calculations.

phrygian
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Homework Statement



I am just trying to convert Btu to J based on the heat capacity of water and it is not giving me the right answer.

Homework Equations





The Attempt at a Solution



Btu = C(water) * m(1 lb) * dt(1 F)

1 lb = 0.454 kg
1 F = 9/5 K

1 Btu = 4.186 kJ/(kg*K) * .454 kg * (9/5)K = 3.42 kJ < should be 1054 J, what am I doing wrong?
 
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Perhaps (5/9) ?
 
I thought 1 F = 9/5*C + 32?
 
You want the amount of energy to heat the water through 1 fahrenheit so it's c->f
 
I have the heat capacity of water in kJ/(kg*K) so arent I converting 1 fahrenheit degree to K?
 
You are calculating the energy needed to heat one pound of water through 1 f
So just like you have the amount of kg in a lb (0.454) you also need the amount of c in an 'f' ie 5/9
 

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