Physics
posted by Dave on .
container holding 340g of water (initially at 14 degrees celsius) is placed in microwave oven, which is turned on for 3 minutes. Assuming all microwave energy is absorbed by water, how much water is left in container?

It would be helpful to know the radiation power of the microwave.

1000W

The microwave oven gives Q = P•t = 1000•180 =1.8•10^5 J.
The amount of heat necessary to heat the water to 100oC
Q1 = c•m1•Δt = 4180•0.340•86 =
= 1.22•10^5 J,
Q2 = Q – Q1 = 1.8•10^5  1.22•10^5 =
= 0.58•10^5 J.
This amount of heat transforms the mass m2 to the vapor
Q2 = r•m2 =2250000•m2,
m2 = 0.58•10^5/2250000 =2.58•10^2 kg =0.0258 kg. 
Mass of left water is m1m2= 0.3400.0258 =0.31422 kg