The burner on an electric stove has a power output of 20 kW

The burner on an electric stove has a power output of 2.0 kW. A 760 g stainless steel tea kettle is filled with 20 degree C water and placed on the already hot burner. If it takes 2.7 min for the water to reach a boil, what volume of water, in cm^3, was in the kettle? Stainless steel is mostly iron, so you can assume its specific heat is that iron. Express your answer to two significant figures.

Solution

Step 1:

determine the amount of heat, which is required to increase the temperature of the tea kettle and water.
Q = m*C*dT
Specific heat of iron = 450 J/kg
Q = 0.760*450*80
Specific heat of water = 4180 J/kg
Q = m*4180*80
Total heat energy required = 0.760*450*80 + m*4180*80
Step 2:
determine the amount of heat energy, which the electric stove supplied.
Power = Energy/time
Energy = Power*time
Power = 2000 W
Time = 2.7*60 = 162 sec
Energy supplied = 2000*162 =324000
Total heat energy required = Energy supplied
0.760*450*80 + m*4180*80 = 324000
Solve for mass of the water.

m = (324000 - 0.760*450*80)/(4180*80) = 0.887 kg = 887 gm

density of water = 1000 kg/m^3= 1 gm/cm^3

Volume = mass/density = 887 cm^3

Let me know if you have any doubt.