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Converting kJmol^-1 to kJkgmol^-1

EDIT: Sorry, title is wrong.

kJmol−1 kJmol^{-1} to kJkg−1 kJkg^{-1}

So this is what I did to try and work this out, say for an enthalpy change of +29.3:

kJmol×1Mr=kJg \frac {kJ}{mol} \times \frac {1}{Mr} = \frac {kJ}{g}

kJg×11000=kJkg \frac {kJ}{g} \times \frac {1}{1000} = \frac {kJ}{kg}

Say the molecular mass is 119.5.

As this is how to convert the units, surely you would apply this to the enthalpy change?

29.3×1119.5×11000=2.45×10−4 29.3 \times \frac{1}{119.5} \times \frac {1}{1000} = 2.45 \times 10^{-4}


This clearly isn't correct, what have I done wrong?
(edited 11 years ago)
Original post by lollage123
EDIT: Sorry, title is wrong.

kJmol−1 kJmol^{-1} to kJkg−1 kJkg^{-1}

So this is what I did to try and work this out, say for an enthalpy change of +29.3:

kJmol×1Mr=kJg \frac {kJ}{mol} \times \frac {1}{Mr} = \frac {kJ}{g}

kJg×11000=kJkg \frac {kJ}{g} \times \frac {1}{1000} = \frac {kJ}{kg}

Say the molecular mass is 119.5.

As this is how to convert the units, surely you would apply this to the enthalpy change?

29.3×1119.5×11000=2.45×10−4 29.3 \times \frac{1}{119.5} \times \frac {1}{1000} = 2.45 \times 10^{-4}


This clearly isn't correct, what have I done wrong?


You multiply by the number of moles in a kilogram ...
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lollage123
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2
That makes sense, K=kj/mol x mol/kg = kj/kg, but why doesn't my method work?

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