## anonymous 4 years ago Calculate the energy in J of 0.32 moles of photons whose frequency is 2.6 x 10^15 ?

1. anonymous

You must know the formula for calculating the energy... in this situation. Do you know the formula?

2. aaronq

E=hv h is planks constant v= frequency this gives you the energy of 1 photon so multiply this by the amount of photons you have: amount of photons = avogadros constant x number of moles

3. anonymous

that v is actually "new (pronounced as new)"

4. anonymous

So @jennilalala with the help of : E = hv formula, can you find the energy by putting the values given ?

5. anonymous

"v" --> $$\large{\color{blue}{\nu}}$$ .... right @aaronq ?

6. anonymous

I am back sorry ahaah. yes i know the formulas. i just dont know what to do if it says ".32 moles of photon.."

7. anonymous

Do you the planck's constant ?

8. anonymous

6.626x10^23 ?? not by heart...yet...

9. aaronq

haha yep, v= "new"

10. anonymous

10^-34

11. anonymous

OK so it is $\large { h = 6.626 \times 10^{-34} m^{-1}}$

12. anonymous

oh wait it is m^2 kg/s

13. anonymous

So right, now solve this : $\large{E = 6.626 \times 10^{-34} \times 2.6 \times 10^{15}}$ What do you get?

14. anonymous

1.73x10^-18

15. anonymous

My calculator says it as : $$\large{\color{blue}{ 17.2276 * 10^{-19}}}$$ that is 1.72276 * 10^{-18}

16. anonymous

OK so now .. this is the energy for $$1$$ photon ... now we to calculate for 0.32 moles of photons.

17. anonymous

See ... no. of photons = Avogadros's constant * no. of moles of photons...

18. anonymous

19. anonymous

6.022x10^23

20. anonymous

Good! So now, solve this one : $\large{\color{red}{\mathbb{No. of Photons}} = \color{blue}{6.022 * {10}^{23}} \times \color{green}{0.32}}$

21. anonymous

1.93x10^23

22. anonymous

then i multiply the two calculations?

23. anonymous

Correct! So this is your No. of photons. Now multiply this result with "1.73 * 10^{-18} "

24. anonymous

3.3x10^-5

25. anonymous

Right!

26. anonymous

not negative typo lol

27. anonymous

No problem.

28. anonymous

So finally you have your correct way, I hope you got it ?

29. anonymous

Yes thank you so much!

30. anonymous

You're welcome @jennilalala . keep up the good work.

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