- #1
clintyip
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Let's say I have a value of:
553 x 10^5 j/kg
How would I convert that to kJ/mol?
553 x 10^5 j/kg
How would I convert that to kJ/mol?
Tomer said:from J to kJ all you need to do is of course to divide in 1000 (=k).
It's simply to look at it like this:
10^3j = kj => j = 10^-3kj
so 553 * 10^5 j = 553 * 10^5 * 10^-3 kj = 553 * 10 ^2 kj
(I substituted j for kg using the upper formula).
About kg=>mol, well, for that you'll have to tell us what's the material involved.
Imagine there are plastic and metal balls. A plastic ball weighs 1 kg and a metal ball 2kg.
It'd be like asking you "how many balls are in a sack weighing 10kg?". If you knew it's plastic balls, you'd say 10. If it were metal balls, you'd say 5.
so 1kg can be 1000 mol and it can be 1 mol => we need more information.
Tomer said:Then use the relation given by rl.bhat and derive the connection between kg and mol. When you say 120, make sure if it's 120 g/mol or 120 kg/mol, and convert fittingly.
Tomer said:How come?
rl.baht wrote: mol = mass / molecular weight.
we want to know the connection between kg and mol. So assume you have 1kg material.
Step 1: convert your molecular weight from 120g/mol => X kg/mol (you do it :-)
Step 2: use rl.baht connection written above, instead of mass you have "kg", and instead of molecular weight you have what you've calculated on Step 1.
Step 3: from the formula of Step 2 isolate kg. You'll get something like kg = Y mol.
Step 4: substitute kg for mol in the expression you've got.
Give it a try, it's important and basic. If you won't make it I'll show you the way.
clintyip said:Step One: 120g/mol => 0.12kg/mol
Step Two: mol = mass/molecular weight
= kg/0.12 = mol
kg = 0.12mol
So 55300kJ/0.12mol
= 460833 kJ/mol
Wow, that's a big number, did I do it right?
The formula for converting J/kg to kJ/mol is to divide the value in J/kg by the molar mass of the substance in kg/mol.
For example, to convert 100 J/kg to kJ/mol for a substance with a molar mass of 20 kg/mol, you would divide 100 by 20 to get 5 kJ/mol.
Converting J/kg to kJ/mol allows us to compare the energy per mass of different substances. It also allows us to use the molar mass of the substance to calculate the energy per mole.
J/kg is a unit of energy per mass, while kJ/mol is a unit of energy per mole. Converting between the two units accounts for the difference in the amount of substance.
Yes, there are other units for energy per mole, such as J/mol and kcal/mol. These units can also be converted to kJ/mol using conversion factors.