[giayojoseph]

Microwave ovens heat food by creating microwave electromagnetic radiation that is absorbed by water molecules in the food. Any material that does not have water in it will not absorb the radiation and will not get hot. Metals reflect the microwaves from their surfaces and disrupt the operation of the oven. Some Australians heat water in microwave ovens to make tea. What is the minimum number of microwave photons with a wavelength of 2.94 mm that will have to be absorbed by a 101.00 gram sample of water to heat it from 25°C to 100°C? (It requires about 315 joules of energy to heat 1 gram of water 75°C)

The answer is 4.71x10^26
However I simply know the answer. I have no clue how to do it.
I have tried to solve it for several hours. Using various combinations of thermochem formulas and wave formula, but no luck.

Anyone mind helping me please?

[renge ishyo]

Use E=n(hc/λ) where n is the number of photons, and the answer should come out O.K. Be sure and multiply the energy for 1g of water by 101 or the exponent might be thrown off a bit.

[giayojoseph]

Thank you so much