## jennilalala Group Title Calculate the energy in J of 0.32 moles of photons whose frequency is 2.6 x 10^15 ? one year ago one year ago

1. SheldonEinstein Group Title

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

2. aaronq Group Title

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. SheldonEinstein Group Title

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

4. SheldonEinstein Group Title

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

5. SheldonEinstein Group Title

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

6. jennilalala Group Title

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. SheldonEinstein Group Title

Do you the planck's constant ?

8. jennilalala Group Title

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

9. aaronq Group Title

haha yep, v= "new"

10. jennilalala Group Title

10^-34

11. SheldonEinstein Group Title

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

12. SheldonEinstein Group Title

oh wait it is m^2 kg/s

13. SheldonEinstein Group Title

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

14. jennilalala Group Title

1.73x10^-18

15. SheldonEinstein Group Title

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

16. SheldonEinstein Group Title

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

17. SheldonEinstein Group Title

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

18. SheldonEinstein Group Title

19. jennilalala Group Title

6.022x10^23

20. SheldonEinstein Group Title

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. jennilalala Group Title

1.93x10^23

22. jennilalala Group Title

then i multiply the two calculations?

23. SheldonEinstein Group Title

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

24. jennilalala Group Title

3.3x10^-5

25. SheldonEinstein Group Title

Right!

26. jennilalala Group Title

not negative typo lol

27. SheldonEinstein Group Title

No problem.

28. SheldonEinstein Group Title

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

29. jennilalala Group Title

Yes thank you so much!

30. SheldonEinstein Group Title

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