## Photoelectric Post-Module [ENDORSED]

princessturner1G
Posts: 31
Joined: Fri Apr 06, 2018 11:05 am

### Photoelectric Post-Module

Hello,
I am having trouble answering the following question on the photoelectric post-module assessment.
Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 105 m.s-1. The work function for sodium is 150.6 kJ.mol-1.

A. What is the kinetic energy of the ejected electron?
B. How much energy is required to remove an electron from one sodium atom?
C. What is the frequency of the incident light on the sodium metal surface? If you can, could you give me a step by step explanation on how to solve this?

What equation would I use and why?

Brynne Keyser 1B
Posts: 31
Joined: Fri Apr 06, 2018 11:03 am

### Re: Photoelectric Post-Module  [ENDORSED]

A) To find the kinetic energy, use KE= 1/2mv^2. the velocity is given and the mass of an electron is a constant
B) divide the work function by avogadro's number, as it is currently in moles.
C) use KE= hv - (work function). you know the work function, the kinetic energy, and Plank's constant, so you can now solve for the frequency.

Hope this helps!

Harmonie Ahuna-1C
Posts: 30
Joined: Fri Apr 06, 2018 11:01 am

### Re: Photoelectric Post-Module

I was also confused about part b for this problem. If we do divide the work function by Avogadro's number as previously suggested, we'd only get one of the answer options if we don't convert 150.6 kJ to 150,600 J, which is something I feel like we'd have to do??

Chem_Mod
Posts: 18400
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 435 times

### Re: Photoelectric Post-Module

The answer above is giving not a detailed step-by-step, but more of a general outline of equations you need to use. You may have to do unit conversions where necessary.