# What is the energy (in kJ/mol) of infared radiation that has a frequency of 1.614 x 1

1. Dec 12, 2009

### stacker

1. The problem statement, all variables and given/known data

What is the energy (in kJ/mol) of infrared radiation that has a frequency of 1.614 x 107 MHz?

2. Relevant equations

E = nhv

3. The attempt at a solution

3 x 6.63 x 10^-34 (J x s) multiplied by 1.614 x 10^7 (MHz) multiplied by (10^6 Hz/1 MHz) multiplied by (1 kJ/ 1000J) = 3.210246 x 10^-20, which is wrong.

Last edited: Dec 12, 2009
2. Dec 12, 2009

### nickdk

Re: What is the energy (in kJ/mol) of infared radiation that has a frequency of 1.614

E = hv
v=1.614x10^13 hz
h = 6.63x10^-34
E = 1.07x10^-20 J
E/1000 = kJ
E = 1.07x10^-23 kJ
per mole
1.07x10^-23 * (6.02 x 10^23 atoms/mol)
E = 6.44 kJ/mol

hope that is clear, any questions lemme know :)

3. Dec 12, 2009

### stacker

Re: What is the energy (in kJ/mol) of infared radiation that has a frequency of 1.614

Yes that's the right answer! But I'm still having trouble understanding why, in terms of units, you can multiply the last step by (6.02 x 10^23 atoms/mol) and still get units of (kJ/mol). When did the unit of "atoms" appear?

Reflection: I made the mistake of not properly converting the Si-Units of "Mega-x" to "x" and neglected the aspect of moles.