avogadro's number

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avogadro's number

Postby megangeorge-1K » Fri Apr 13, 2018 7:54 pm

in lecture today, Dr. Lavelle mentioned something about having to divide by avogadro's number when regarding the energy it takes to remove an electron. I'm not quite sure why it is we have to divide by avogradro's number or when we would have to. I'm also not sure if this question makes any sense lol.

Thank you!

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Re: avogadro's number

Postby Sollie1G » Fri Apr 13, 2018 7:57 pm

I found this but I'm not sure if it is enough to answer your question

"The initial energy state is 1 (the only energy state the hydrogen atom can have) and the inverse of 1 is 1. The difference between 1 and 0 is 1. ... This is the first ionization energy of the hydrogen atom. Multiply the ionization energy by Avogadro's number, which gives the number of particles in a mole of substance."

Liliana Rosales 1E
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Re: avogadro's number

Postby Liliana Rosales 1E » Fri Apr 13, 2018 11:18 pm

Dr. Lavelle was saying that we would have to divide the energy by the avogadro's number because the energy is usually given per mole. For problems dealing with the photoelectric effect, you would want to find the energy per photon not per mole. I hope this somewhat clarifies your question.

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Re: avogadro's number

Postby EllenRenskoff-1C » Sat Apr 14, 2018 10:37 am

Did Dr. Lavelle mention if it will be specified in the problem whether we are looking for energy per photon versus energy per mole of photon, or is it implied that it's per photon when we're talking about the photoelectric effect? (I hope my question makes sense.)

Jose Hernandez 1D
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Re: avogadro's number

Postby Jose Hernandez 1D » Sun Apr 15, 2018 2:44 pm

The best way to answer this question would be by asking your TA or Lavelle himself

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Re: avogadro's number

Postby Chem_Mod » Sun Apr 15, 2018 7:23 pm

When we talk about E= hv, it is talking about an energy of a photon. A photon is a singular object, so it must be expressed in terms of "per particle". So if you have a quantity that is given in terms of moles, there is a disconnect in the comparison since you are trying to compare "per particle" to "per mole" quantity. That is why you need to use Avogadro's number to have the right comparison. He was referring to a potential situation like this when talking about this.

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