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balandron [24]
4 years ago
10

A laser pulse with wavelength 545 nm contains 4.85 mJ of energy. How many photons are in the laser pulse?

Chemistry
1 answer:
dusya [7]4 years ago
3 0

<u>Given</u>:

Wavelength (λ) of the laser pulse = 545 nm = 5.45 * 10⁻⁹ m

Total energy of pulse = 4.85 mJ

<u>To determine:</u>

The number of photons in the laser of a given energy

<u>Explanation:</u>

Energy per photon (E) = hc/λ

where h = planck's constant = 6.626 *10⁻³⁴ Js

C = speed of light = 3*10⁸ m/s

λ = wavelength

E = 6.626 *10⁻³⁴ Js* 3*10⁸ms-1 /5.45 * 10⁻⁹ m = 3.65 * 10⁻¹⁹ J

Now,

# photons = total energy/Energy per photon

                 =  4.85 * 10⁻³ J* 1 photon / 3.65 * 10⁻¹⁹ J = 1.32 * 10¹⁶ photons

Ans: the laser pulse contains 1.32 * 10¹⁶ photons

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3 years ago
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One gram of alum, KAl(SO4)2.12H2O, contains 1.3 × 1021 Al atoms. How many oxygen atoms are contained in 1.0 g alum?
Roman55 [17]

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So, if you have 1.3 × 10^21 Al atoms, you have 20 * 1.3 × 10^21 O atoms will now be equal to 2.6 * 10^22 atoms of O.

6 0
3 years ago
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How many atoms are in a sample of 175 grams of sodium (na)? 1.42 × 10^27 atoms 4.58 × 10^24 atoms 6.68 × 10^-21 atoms 1.26 × 10^
Alenkasestr [34]
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5 0
4 years ago
Find the molality of this aqueous solution 15.0% by mass kBr (119g/mol).
Vsevolod [243]

Answer:

we will take a 100g sample of this solution for our convenience

so , there is 15 g kBr in this 100g solution

we know that molality is the number if moles of solute / mass of solvent in kg

we need to find the number of moles in 15g kBr

no of moles = 15/119 s

moles  = 0.126 moles/ 100g

multiplying both the numerator and the denominator by 10 to get 1 kg in denominator

=  1.26 moles / 1 kg

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would appreciate a brainliest

3 0
4 years ago
How many mL of 0.100 M NaCl would be required to make a 0.0365 M solution of NaCl when diluted to 150.0 mL with water?
Tatiana [17]

Answer:

54.75 mL

Explanation:

First calculate the number of moles of NaCl in the 150mL solution of NaCl

0.0365 moles should be present on 1000cm3 or 1dm3 of water.

1L = 1 dm3

1 mL = 1 / 1000 dm3

150 mL = 150/1000 dm3 = 0.15 dm3

If x moles are present in 0.15 dm3,

x/ 0.15 = 0.0365

We get x= 0.0365 × 0.15 mol

Now x amount of moles should be taken from the initial 0.100 M NaCl solution

So 0.1 moldm-3 = 0.0365× 0.15 mol / V

we get V = 0.05475 dm3

V= 0.05475 L

V= 54.75 mL

3 0
3 years ago
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