How long will the sun burn if only combustion is happening.

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SUMMARY

The discussion centers on calculating the duration the sun would burn if its energy source were solely the combustion of methane. Given the sun's mass of 2 x 1030 kg and an energy output of 3.9 x 1026 watts, the combustion enthalpy of methane is -802 kJ. The participant debated whether to use the mass of methane (16 g/mol) alone or include the mass of oxygen (32 g/mol) in the calculations, concluding that both must be considered for accurate results.

PREREQUISITES
  • Understanding of combustion chemistry, specifically methane combustion.
  • Familiarity with thermodynamics, particularly enthalpy changes.
  • Basic knowledge of energy calculations involving watts and time.
  • Ability to perform stoichiometric calculations in chemical reactions.
NEXT STEPS
  • Research the thermodynamic properties of methane combustion.
  • Learn about energy output calculations in chemical reactions.
  • Study stoichiometry in combustion processes.
  • Explore the implications of energy sources on stellar lifespans.
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Students in chemistry or physics, educators teaching combustion and thermodynamics, and anyone interested in astrophysics and energy calculations.

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Homework Statement


The sun has a mass of 2*10^30kg and gives off energy at a rate of 3.9*10^26 watts. If the source of the sun's energy energy were ordinary combustion of methane how long will it last.




Homework Equations



delta Enthalpy of the combustion of methane is -802 kj. Energy equals watts times time.


The Attempt at a Solution



All I need to know is this. When I do this problem do I use the mass of both the methane and 2O_2 which is 80 grams per mole or just the methane which is 16 grams per mole. I did this problem using 80 grams per mole because that's the mass of the fuel that is burning that gives off 802 kj of energy.
 
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Well, it seems like to do it right you need to include the mass of both combustion products. You can't burn the methane without oxygen, right?
 

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