[lilns8252]

I needed help with one question in a set of questions. The questions that are before the one i need help with are: (need help with bold ones)
One type of sunburn occurs on exposure to UV light of wavelength in the vicinity of 310 nm.

a. What is the energy of a photon of this wavelength?
    E=6.41×10−19 J

b. What is the energy of a mole of these photons?
    E=3.86*10^5 J

c. How many photons are in 1.20 mJ burst of this radiation??
    N=? photons

d. These UV photons can break chemical bonds in your skin to cause sunburn—a form of radiation damage. If the 310 nm radiation provides exactly the energy to break an average chemical bond in the skin, estimate the average energy of these bonds in kJ/mol?
     average energy= kJ/mol

[Borek]

I have poured a liter of water from sixth floor balcony. How many 0.05mL droplets were formed?

[syd]

I needed help with one question in a set of questions. The questions that are before the one i need help with are: (need help with bold ones)
One type of sunburn occurs on exposure to UV light of wavelength in the vicinity of 310 nm.

a. What is the energy of a photon of this wavelength?
    E=6.41×10−19 J

b. What is the energy of a mole of these photons?
    E=3.86*10^5 J

c. How many photons are in 1.20 mJ burst of this radiation??
    N=? photons

d. These UV photons can break chemical bonds in your skin to cause sunburn—a form of radiation damage. If the 310 nm radiation provides exactly the energy to break an average chemical bond in the skin, estimate the average energy of these bonds in kJ/mol?
     average energy= kJ/mol

For c, there is an equation that you can use.  It's something like #photons = ePulse/ePhoton.  Both are supposed to be measured in J, so you have a simple conversion to do first.

Good luck with D

[Xenophilius]

You can use the equation: E=(n*h*(speed of light))/Wavelength. In nanometer the product h*(speed of light) comes out to be nearly 1240nm. Hence your answer is simply E/4.