Combustion Equation: C8H18 + O2 + N2 = CO2 + H2O

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In summary, the conversation discusses the calculation of molal analysis and dew point for the products of combustion when burning C8 H18 with 200% theoretical air. The question is raised about choosing between two different combustion equations and how it affects the calculation of partial pressure of water. The answer is that the first equation is the correct choice for obtaining accurate results.
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radwa
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Will you please help me...
It is required to determine the molal analysis of the products of combustion when C8 H18 is burned with 200% theoretical air, and determine the dew point (saturation temperature corresponding to the partial pressure of water present in this equation) of the products if the pressure is 0.1 MPa
This is the combustion equation the book used to solve this problem with
C8 H18 + 12.5(2)O2 +12.5(2)(3.76)N2 =8CO2 +9H2 O+12.5O2 +94N2
My question is when balancing this equation we might have chosen to write it as
C8 H18 + 6.75(2)O2 +6.75(2)(3.76)N2 =8CO2 +9H2 O+O2 +50.76N2
But if we changed the equation like this, in getting the partial pressure of water, instead of calculating it by obtaining the mole percent of the water from the first equation which is 7.29% and multiplying it by 0.1 MPa to have apartial pressure of 7.29 KPa we will get a very different result using the second equation .How do we know that we have to write the first and not the second equation?
 
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  • #2
Originally posted by radwa
Will you please help me...
It is required to determine the molal analysis of the products of combustion when C8 H18 is burned with 200% theoretical air

(snip)

How do we know that we have to write the first and not the second equation? [/B]
 

1. What is the balanced chemical equation for combustion of C8H18?

The balanced chemical equation for combustion of C8H18 is C8H18 + 12.5O2 + 47.5N2 = 8CO2 + 9H2O + 47.5N2.

2. What are the reactants in the combustion equation for C8H18?

The reactants in the combustion equation for C8H18 are C8H18, O2, and N2.

3. What are the products in the combustion equation for C8H18?

The products in the combustion equation for C8H18 are CO2 and H2O.

4. How many moles of oxygen are needed to completely react with one mole of C8H18?

To completely react with one mole of C8H18, 12.5 moles of oxygen are needed.

5. What type of reaction is the combustion of C8H18?

The combustion of C8H18 is an exothermic reaction, meaning it releases heat and energy.

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