## question 27

$E=hv$

Moderators: Chem_Mod, Chem_Admin

Josh Moy 1H
Posts: 58
Joined: Thu Jul 13, 2017 3:00 am

### question 27

For question 27, it wants moles of photons, and i found energy to be 4.7x10^-19 J/photon, but when converting to just photons the solution Manual turns the 4.7x10^-19 into photons/J to cancel out jules with the 64J. Why did they do this

Miguel Velasco 2J
Posts: 40
Joined: Fri Sep 29, 2017 7:07 am
Been upvoted: 1 time

### Re: question 27

Remember! In E=hv, E is energy PER photon. We have 4.7x10^-19J.photon^-1.
We then multiply 64J (1mole/6.022x10^23J) and get 1.4x10^20 photons (and jewels canceled out).

Adrian Franco 3H
Posts: 20
Joined: Fri Sep 29, 2017 7:06 am
Been upvoted: 1 time

### Re: question 27

Alternatively, you could also divide to cancel out units:

64 J / [(4.7 x 10^-19) J.photon^-1] = 1.4 x 10^20 photons.

Notice how the joules cancel out!

Return to “Einstein Equation”

### Who is online

Users browsing this forum: No registered users and 1 guest