## 7th edition 1B. 7

$E=hv$

Alyssa Bryan 3F
Posts: 61
Joined: Fri Sep 28, 2018 12:26 am
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### 7th edition 1B. 7

In part B of this question, it asks for how much energy is emitted by 5.00 mg of sodium atoms and in part c is asks for how much energy is emitted by 1.00 mol of sodium atoms, both emitting light at a wavelength of 589 nm. How are you able to go from grams and mols of sodium atoms to joules?

Krisdylle Repollo 4H
Posts: 33
Joined: Fri Sep 28, 2018 12:28 am

### Re: 7th edition 1B. 7

For part B, you have to find the molar mass of sodium and multiply it by Avogrado's number and the energy you found in part A. So the equation would look like this:

(5.00 x 10^-3 g Na/22.99 g•mol Na) x (6.022 x 10^23 atoms/mol) x (3.37 x 10^-19 J/atom)

= 44.1 J

The units cancel and you're left with Joules as the remaining unit for your answer.

Krisdylle Repollo 4H
Posts: 33
Joined: Fri Sep 28, 2018 12:28 am

### Re: 7th edition 1B. 7

And for part C, since you're already given 1 mol of Sodium atoms, you know that 1 mol equals 6.022 x 10^23 atoms/mol. So you multiply this number to the energy you found in part A to find your answer.