7.00ml ampule of a 0.150 mole solution naphthalene in hexane is excited with a flash of light. the naphthalene emits 19.9j of energy at an average wavelength of 349 nmmi. what percentage of naphthalene molecules emitted a photon?

Mole of naphthalene solution = 0.150

Molecules of naphthalene in the solution = 0.150 mol x (6.022 x 10²² molecules/1 mol) = 9.033 x 10²² molecules

Energy of a photon,

E = hγ = h. c/λ

where h is Planck's constant (6.626 x 10⁻³⁴) and γ is the frequency of light, c is the speed of light (3 x 10⁸) and is the λ wavelength of light.

Given, wavelength of light = 349 nm = 349 x 10⁻⁹ m ( 1 nm = 10⁻⁹ m)

Energy of one photon is,

E = 6.626 x 10⁻³⁴Js x (3 x 10⁸ms⁻¹ / 349 x 10⁻⁹ m)

E =  5.7 x 10⁻¹⁹ J

Energy emitted by naphthalene = 19.9 J

Therefore, the number of photons emitted = 19.9 J / 5.7 x 10⁻¹⁹ J = 3.5 x 10¹⁹

Percentage of naphthalene molecules that emitted a photon is

(photons emitted / total number of naphthalene) x 100

(3.5 x 10¹⁹/ 9.033 x 10²²) x 100

0.0387%

Thus 0.0387% naphthalene molecules emitted a photon.

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

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