i need my specific heat capcity converted from j/mol K to j/Kg K?
3 Answers
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The difference is the conversion of mole to kg, and you need the type of material to do that.
For example, iron:
atomic number 26
atomic weight 55.845 g/mol
1 mole = 55.8 g = 0.0558 kg
so it it's iron
SH = 25 J/molK
25 J/molK x 1mol/0.0558 kg = 448 J/kgK
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If you have the value of molar mass of a substance , then multiply it by specific heat of that substance given in J/(g K) to get j/mol K.
Please read below:
j/mol K is the unit of molar heat capacity.
j/Kg K is the unit of specific heat capacity.
The Molar Heat Capacity is just like the specific heat capacity in Chemistry, except its units differ.
A specific heat capacity is the amount of energy necessary to increase the temperature of a kilogram of that substance by one Kelvin.
Molar heat capacity is the amount of energy necessary to raise one mole of substance by one degree Kelvin.
One mole of a substance is exactly 6.02x10^23 atoms or molecules of that substance. If we know how many kilograms we have of a substance, and we also know the atomic weight of that substance, we can find out how many moles we have of the substance.
We can therefore convert the specific heat capacity of a kilogram of a substance to the molar heat capacity in the following way:
Cn = Cp*m mole
where ,
Cn is the molar heat capacity of the substance,
Cp is the specific heat, and mmole is the mass per mole of the substance, which is essentially the atomic weight (measured in g/mol).
The SI units for molar heat capacity are joules/(mole.Kelvin).
The molar mass of water is obtained by multiplying each of these parts by the corresponding masses of the elements:
2 x (1 g/mol hydrogen) + (16 g/mol oxygen) = 18 g/mol water
Multiply the specific heat of the substance by the molar mass of the substance. This results in the molar heat capacity of the substance, in joules per mol K. For water, for example, the specific heat is given as roughly 4.184 J/(g K). Multiply this by the molar mass:
4.184 x 18 = 75.312 J/(mol K)
Source(s): http://www.ehow.com/how_6184868_calculate-molar-he... -
Not completely sure about this