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Andrew [12]
3 years ago
13

A laser pulse with wavelength 555 nm contains 4.40 mj of energy. how many photons are in the laser pulse?

Chemistry
1 answer:
Diano4ka-milaya [45]3 years ago
5 0

Wavelength is the ratio of speed of light and frequency:

wavelength = speed of light / frequency 

where frequency is: (c is speed of light)<span>
freq = c / wavelength = 3E8/550E-9 = 5.45E14 Hz 

We know that photons have energy E = hf = 6.626E-34 Js * 5.45E14 Hz = 3.61 E-19 J 

Therefore if it has 4.40 mJ of energy, the pulse has: 
<span>4.40E-3/3.61E-19 = 1.22E16 photons</span></span>

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3 years ago
28 ml of 0.10 m hcl is added to 60 ml of 0.10 m sr(oh)2. determine the concentration of oh− in the resulting solution.
Blababa [14]
Here is an acid-base reaction. Hydrochloric acid (HCl) reacts with strontium hydroxide [ Sr(OH)2 ]

Ions H+ and OH- neutralize each other. If the amounts are not equal, one of them will be in excess. 
Follow the steps as

1. Find moles of ions: mole= Molarity * Volume (in liter) ; n= M * V OR millimole = Molarity * Volume (in ml) ;
2. Write the equation
3. Find out excess ion
4. Use final volume (V acid + V base ) to calculate concentration of excess ion.

n HCI = 28 ml * 0.10 M = 0.28 mmol, releases 0.28 mmol H+ ions
n Sr(OH)2= 60 ml * 0.10 M= 0.60 mmol, releases 2* 0.60=1.20 mmol OH- ions
since Sr(OH)2⇒ Sr2+ + 2OH-

Neutralization reaction is OH- + H+ ---> H2O. The ratio is 1:1. That means 1 mmol hydroxide ions will neutralize 1 mmol hydrogen ions. Since OH- ions are greater in amount, they will be in excess

n(OH-) - n(H+)= 1.20 - 0.28 = 0.92 mmol OH- ions UNREACTED.

Total volume= V acid + V base= 28 ml + 60 ml = 98 ml

Molarity of OH- ions= mole / Vtotal = 0.92/98= 0.009 M

The answer is 0.009 M.


5 0
3 years ago
Read 2 more answers
____ HBr + ____ Mg(OH)2 ---&gt; ____ MgBr2 + ____ H2O
swat32
Hello Camkirkland,
I think that you are trying to balance this equation.
In order to balance a chemical equation, the numbers of atoms of each element must be equal on both sides of the equation.

In this particular equation, the answer would be (2) HBr + (1) Mg(OH)2 ---> (1) MgBr2 + (2) H2O.

Hope this answers your question!
4 0
3 years ago
A rigid vessel contains water at 0.15 MPa (at 25 °C). The vessel is heated to the critical point of water. Calculate the fractio
pishuonlain [190]

Answer:

0.8078 Kg

Explanation:

Pressure of water = 0.15 MPa = 1.5 bar

At critical point of water ,temperature = 647 K=374°C

From the ideal gas equation

P×V= m×R×T

Let us assume volume = 1 m^3

1.5 x 105 x 1 = m x 287 x 647

m= 0.8078 kg

the fraction of mass of liquid at 25°C.

4 0
3 years ago
Using Argn (n= –2, –1, 0, +1, +2, etc.) to represent the different charge species of Arginine, what is the dominant species of A
fredd [130]

Answer:

Explanation:

From the sorensen equation; pH = -Log[H+]

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H+ = 0.001995M = Hydrogen ion concentration

Basically, the more the charges, the higher the hydrogen ion concentration stand vice versa. +2 has the highest concentration.

6 0
3 years ago
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