Question

Calculate the energy in J of 0.32 moles of photons whose frequency is 2.6 x 10^15 ?

Answer 1

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

Do you know the formula?

Answer 2

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

Answer 3

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

Answer 4

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

Answer 5

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

Answer 6

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

Answer 7

Do you the planck's constant ?

Answer 8

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

Answer 9

haha yep, v= "new"

Answer 10

10^-34

Answer 11

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

Answer 12

oh wait it is m^2 kg/s

Answer 13

So right, now solve this :

\[\large{E = 6.626 \times 10^{-34} \times 2.6 \times 10^{15}}\]

What do you get?

Answer 14

1.73x10^-18

Answer 15

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

Answer 16

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

Answer 17

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

Answer 18

You know avogadro's constant?

Answer 19

6.022x10^23

Answer 20

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

Answer 21

1.93x10^23

Answer 22

then i multiply the two calculations?

Answer 23

Correct! So this is your No. of photons.

Now multiply this result with "1.73 * 10^{-18} "

Answer 24

3.3x10^-5

Answer 25

Right!

Answer 26

not negative typo lol

Answer 27

No problem.

Answer 28

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

Answer 29

Yes thank you so much!

Answer 30

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