a large container holding 340g of water, initially 14°C is placed in a microwave oven. the magnetron in the microwave oven can produce 900W of electromagnetic radiation. the microwave is turned on for 3 minutes. assuming all microwave energy is absorbed by the water, how much water is left in the container?
Physics - Elena, Thursday, April 26, 2012 at 6:45am
The microwave oven gives Q = P•t = 900•180 =1.62•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 = 1.62•10^5 - 1.22•10^5 = 0.4•10^5 J.
This amount of heat transforms the mass m2 to the vapor
Q2 = r•m2 =2250000•m2,
m2 = 0.4•10^5/2250000 =1.78•10^-2 kg =0.0178 kg.
Mass of left water is m1-m2= 0.340-0.0178 =0.322 kg
Physics - Rodney, Thursday, April 26, 2012 at 8:26pm
Thank you so much Elena, so saved me. Beautiful name you have.