Chemistry please help
posted by Saira .
Suppose that the microwave radiation has a wavelength of 12.4 cm. How many photons are required to heat 255 mL of coffee from 25.0 C to 62.0 C? Assume that the coffee has the same density, 0.997 g/mL, and specific heat capacity, 4.184 J/(g/ K), as water over this temperature range.
I am not sure how to find the answer

NVM got it

Energy/photon = hc/wavelength.
Remember to change wavelength meters and use c in m/s.
heat required = mass x density x specific heat x delta T. Everything is here to calculate heat required.
Knowing heat/photon and the total energy required you can calculate the number of photons required. 
2.17*10^28