## What to do when a Energy is given in kJ*mol-1?

$c=\lambda v$

E_Villavicencio 2N
Posts: 26
Joined: Wed Sep 21, 2016 2:59 pm

### What to do when a Energy is given in kJ*mol-1?

When a problem gives you an energy needed to break a C-C bond in kJ*mol, and asks you for the wavelength required in order to break that bond, do you need to convert that energy in J (by multiplying by 10^3) and then divide it by the Avogadro's number? I am not sure about the moles part (whether you should divide the energy given by 6.022*10^23), because the fact that it is a bond confuses me a little bit.

mikezargari
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### Re: What to do when a Energy is given in kJ*mol-1?

That is exactly what you do. You're given the energy per mol but you want the total energy which is why you would do that conversion.

Audrey_Hall_2I
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### Re: What to do when a Energy is given in kJ*mol-1?

Did we ever do this in lecture?

paulapedrani
Posts: 27
Joined: Wed Sep 21, 2016 2:56 pm

### Re: What to do when a Energy is given in kJ*mol-1?

We never did this in lecture, but yes, you divide by Avogadro's number. For that specific question, once you got the energy, you have find the wavelength and then determine if it was in the range of visible light. (visible light being from 400-700 nm)

Posts: 17
Joined: Wed Sep 21, 2016 2:58 pm

### Re: What to do when a Energy is given in kJ*mol-1?

Is there like a trick or something to memorizing the wavelengths of each light wave? No matter how much I try to remember them, they just seem to slip my mind.

Kiara Quinn 3B
Posts: 20
Joined: Sat Jul 09, 2016 3:00 am

### Re: What to do when a Energy is given in kJ*mol-1?

In terms of memorizing the wavelengths, just remember that 400 nm is violet and 700 nm is red. Anything slightly less than 400 nm would be in the UV region. Anything slightly greater than 700 nm is infrared region.

paulapedrani
Posts: 27
Joined: Wed Sep 21, 2016 2:56 pm

### Re: What to do when a Energy is given in kJ*mol-1?

and make sure you know that nm is x 10^-9!