Convert Enthalpy of Combustion (kj/kmol) to kj/kg

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In summary, the person is requesting help with converting enthalpy of combustion values from kj/kmol to kj/kg. They have been trying to use mols multiplied by molecular weight, but have not been getting the desired answer. Another person suggests multiplying the kj/kmol value by (1Kg/molar mass) to get a 1Kg equivalent in moles. However, there is some confusion on whether it is kJ/kmol or kJ/mol and it is noted that the molecular weight converts moles into grams, not kg.
  • #1
skaboy607
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Hi

I'm studying combusion at the moment and was wondering how to convert the enthalpy of combustion values given in Steam Tables in kj/kmol to kj/kg? I have been trying to do mols multiplied by molecular weight, but this hasn't been giving me the answer I want.

Thanks for your help.
 
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  • #2
I didnt really ask in the other thread.

Why do you want to do this anyway? I've never come across a situation where it would be useful.

I would think you would need to times the kj/kmol value by (1Kg/molar mass) as you want 1Kg eqivilant in moles.
 
  • #3
Is it kJ/kmol or kJ/mol (no "k" prefix on mol)?

It does look like a straightforward moles→mass conversion problem. However, note that the molecular weight converts moles into grams, not kg. Perhaps the problem is there?
 

What is enthalpy of combustion?

Enthalpy of combustion is a measure of the amount of heat released when a substance undergoes complete combustion with oxygen.

Why do we need to convert enthalpy of combustion from kj/kmol to kj/kg?

Kj/kmol is a unit of measurement for the amount of substance, while kj/kg is a unit of measurement for mass. Converting from kj/kmol to kj/kg allows us to compare the enthalpy of combustion of different substances on a per unit mass basis.

How do you convert enthalpy of combustion from kj/kmol to kj/kg?

To convert from kj/kmol to kj/kg, you will need to know the molar mass of the substance. The conversion formula is: enthalpy of combustion (kj/kg) = enthalpy of combustion (kj/kmol) / molar mass (kg/kmol).

What is the significance of enthalpy of combustion in chemistry?

Enthalpy of combustion is an important concept in chemistry as it allows us to understand and quantify the energy changes that occur during combustion reactions. It is also useful in determining the energy efficiency of different fuels.

Can enthalpy of combustion be negative?

Yes, enthalpy of combustion can be negative if the reaction releases more energy than it consumes. This is often seen in exothermic reactions, where the products have a lower enthalpy than the reactants.

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