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UkoKoshka [18]
3 years ago
15

How many photons are produced in a laser pulse of 0.862 J at 691 nm?

Chemistry
1 answer:
Inga [223]3 years ago
4 0
To calculate how many photons are in a certain amount of energy (joules) we need to know how much energy is in one photon.
Start by using two equations:
Energy of a photon = Frequency * Planck's constant (6.626 * 10^(-34) J-s)
Speed of light (constant 3 * 10^8 m/s) = Frequency * Wavelength
Which means:
frequency = Speed of Light / Wavelength
So energy of a photon = (Speed of light * Planck's constant)/(Wavelength)
You may have seen this equation as E = hc/<span>λ</span>
We have a wavelength of 691 nm or 691 * 10^-9 meters
So we can plug in all of our knowns:
E = (6.626 * 10^(-34) J-s) * (3.00 * 10^8 m/s) / (691 * 10^-9 m) = 
2.88 * 10^(-19) joules per photon
Now we have joules per photon, and the total number of joules (0.862 joules)
,so divide joules by joules per photon, and we have the number of photons:
0.862 J/ (2.88 * 10^(-19) J/photon) = 3.00 * 10^18 photons.

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Consider the reaction. A(aq) = 2 B(aq) Kc = 6.90 x 10 6 at 500 K If a 3.00 M sample of A is heated to 500 K, what is the concent
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0.004548 M is the concentration of B at equilibrium at 500 K.

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                         A(aq) ⇆ 2 B(aq)

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At equilibrium   3.00 -x    2x

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x = 0.002274 M

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[A] = (3-x) = 3 M - 0.002274 M =2.997726 M

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Answer:

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Explanation:

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*Standard Heat of Formation by definition is the heat gained or lost on formation of a substance (compound) from its basic elements in standard state.

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