college chemistry
posted by shylo .
I am having a problem with this problem from my homework. I need some help on this problem.
Microwave ovens work by irradiating food with microwave radiation, which is absorbed and converted into heat. Assume radiation with wavelength=15.0cm is used and that all the energy is converted to heat. How many photons are necessary to raise the temperature of a 350mL quantity of water from 20.0 degree C to 95.0 degree C?

(a)
The energy of a photon is given by:
E = hf
h = Planck's constant (look it up)
f = frequency = speed of light / wavelength
f = (3.00x10^8 m/s) / (0.15m) = _____?
E = ______?
(b)
∆T = T2  T1 = ____?
Heat needed = (4.18 J/g.C)(grams H2O)(∆T)
Heat = _________?
(c)
Divide the heat calculated in part (b) by the energy per photon calculated in part (a)