## How to find the kinetic energy of ejected electrons?

elizabethrojas1G
Posts: 44
Joined: Fri Sep 25, 2015 3:00 am

### How to find the kinetic energy of ejected electrons?

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. What is the kinetic energy of the ejected electron?

I did see a previous post with this question but it wasn't clear to me how to actually solve it. If I used hv- work function = Ek would there be any way to find v or am I using the wrong equation?

Chem_Mod
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Joined: Thu Aug 04, 2011 1:53 pm
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### Re: How to find the kinetic energy of ejected electrons?

Kinetic energy is calculated through the formula KE= 0.5 m*v2, where m is the mass, in this case the ejected electron mass, and v is the velocity which is given in the question.

elizabethrojas1G
Posts: 44
Joined: Fri Sep 25, 2015 3:00 am

### Re: How to find the kinetic energy of ejected electrons?

thank you

Lauren Wong 3K
Posts: 20
Joined: Wed Sep 21, 2016 2:56 pm

### Re: How to find the kinetic energy of ejected electrons?

How do you find the mass of the ejected electron?

Chem_Mod
Posts: 18739
Joined: Thu Aug 04, 2011 1:53 pm
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### Re: How to find the kinetic energy of ejected electrons?

The mass of an electron is a constant, so it's given to you and it's always the same.