Photons are a fundamental particle in nature. They are the “packets” of energy that light is made of. Every wavelength of visible light (380-760 nm) has a specific number of photons per second.
These photons have a specific energy, which is how much energy each photon contains. This value is denoted in joules per mole, or kj/mol.
Knowing how many photons of what wavelength make up a certain amount of light can help you calculate how much energy the light contains. By doing this for all the wavelengths of visible light, you can find out how many kilojoules (kJ) of energy one cubic meter (m^3) of air contains!
This article will discuss how to do this and give you the answers for air at normal atmospheric pressure.
Multiply the frequency by the wavelength
The next step is to multiply the frequency of the photons by the wavelength. This gives you the energy per photon, or how much energy each photon contains.
Since we are working with infrared photons, which have a longer wavelength than visible light photons, we need to take that into account when calculating how much energy each photon contains.
Calculating the total energy of these 3 moles of photons is a little tricky at first, but once you get the hang of it, it’s a pretty useful skill!
As mentioned above, the average frequency of these photons is 3 x 10^12 Hz, and their wavelength is 656 nm. To find how many joules (or kilojoules) of energy are contained in each photon, we simply need to multiply one another.
Multiply by the number of photons
The next step is to multiply the number of moles of photons by the energy per mole of photons, which is 8.99 x 10-14 j/n. This gives you 8.99 x 10-13 j.
Then, you must convert this to kilojoules by multiplying by one thousand, which gives you 9.88 kilojoules (kJ).
So, how much energy does 3.0 moles of photons contain? The answer is 29.76 kJ!
Remember that a mole is a unit of measure equal to 6.02 x 1023 items (in this case, photons). By determining how many moles of photons you have, you can find the total amount of energy contained within them. You just have to be careful to use the correct conversion when doing so.
Divide by 1000
Now that you know the specific energy of one mole of photons, you can figure out how much energy all of the photons in a given light source contain. You just need to know the wavelength of the light and the number of moles of photons.
You divide the Specific Energy by one thousand (1000) to get Universal Energy, so 3.0 moles of photons with a wavelength of 655 nm containing energy has:
Universal Energy = 3.
Obtain the energy in kj/mol
Once you have determined the number of moles of a substance, you can find the energy in kj/mol by using the following formula:
Energy in kj/mol = (mass in grams / Molar mass) x Avogadro’s number
Where Avogadro’s number = 6.022 × 1023 molecules per mole. This is known as a mol unit.
So, how much energy (in kj) do 3.0 moles of photons, all with a wavelength of 655 nm, contain? We will use the formula to find out!
First, we need to find out how many grams 3.0 moles of photons weigh. We already know that 3.0 moles of photons weigh 602 grams, so we will put that into the first part of the equation: Energy in kj/mol = (mass in grams / Molar mass) x Avogadro’s number. We then need to find out Avogadro’s number, so we will use Google and search “Avogadro’s Number facts” and see if there is an answer on there.
Answer:
There are 602 grams / 3 millionths mole = 2.8 × 10−5 kg.
Avogadron’s Number is 6.022 × 1023.
Therefore, Energy In KJ/MOL = 2 800 000 000 000 000 KJ/MOL[1].
We got this by putting 2 800 billion into the equation and solving for “KJ/MOL”.
Convert to kj
Now that you can calculate the molar energy of photons, you can convert this to joules (j) and kilojoules (kj)!
One mole of photons with a wavelength of 655 nm has a molar energy of 2.2×10−6 kj. This is the same as saying that one mole of photons with a wavelength of 655 nm has an energy of 2.2 eV per photon.
One eV is one elementary unit of electric charge, which is the amount of charge carried by one electron. An electron volt (eV) is the amount of potential or kinetic energy that an electron has due to moving through a voltage difference of 1 volt.
Thus, one eV is the amount of energy carried by one photon via its electric field.
Round to two significant digits
Now that you know how to calculate the molar energy of photons, you can calculate the total energy of a certain number of photons. You can calculate the total energy of a certain number of photons with all the same wavelengths and intensities.
According to our calculations, one mole of 655-nm wavelength photons with 3 atoms per molecule has an absorption capacity of around 1.5 × 10−5 J/mol. That is not very much!
It would take quite a few such molecules to absorb enough light to generate any kind of chemical reaction. It would also take a large amount of these molecules to absorb enough light to generate any kind of heat change.
Write your answer
So, let’s look at the next point: how much energy do 3.0 moles of photons contain?
Photons are a particle of light. A photon is a quantum of light, similar to how an atom is a quantum of matter. The difference is that atoms can contain different elements, whereas photons are pure light without any substance.
When we speak of moles in chemistry, we are talking about the number of particles in a given volume. For example, one mole of something is the number of particles it contains when it fills up a one-liter bottle.
So, to answer the question: one mole of photons contains 3.89 × 10−8 joules (or 3.89 × 10−7 kj) per photon. This is based on the average visible light spectrum.
