Question

During photosynthesis, chlorophyll-a absorbs light of wavelength 440 nm and emits light of wavelength 670nm. What is the energy available for photosynthesis from the absorption-emission of a mole of photons ?​

Answer 1

Answer:

The answer is 93.3 KJ/mol .

Explanation:

We know that  

ΔE = (Nhc/ λ)absorbed - (Nhc/ λ)evolved

Here  "ΔE" is the difference in energy, "N" is Avogadro's number, "h" is plank's constant and "c" is the speed of light in vacuum.

Now do some calculations:

Now rearrange the equation by taking Nhc common:

ΔE = Nhc (1/ λabsorbed  - 1/ λevolved)

 = 6.023 x 10 ^23 x 6.626 x 10 ^-34 x 3 x 10 ^8 (1 / 440x10 ^-9 - 1/670x10 ^-9)

     = 0 .1197 ( 0.00272 x10 ^9 - 0.00149 x10 ^9)

     = 0 .1197 ( 2.272 x 10 ^-3 x10 ^9 - 1.492 x10 ^-3x10 ^9)

     = 0.1197 (2.272 x 10 ^6 - 1.492x10 ^6)

     = 0.1197 (2.272 - 1.492) x 10^6

     = 0.1197 x 0.78 x 10^6

     = 0.0933 x10^6

     = 93.3 x10^3 J/mol = 93.3 KJ/mol