A water heater contains 59 gallons of water how many kilowatt hours of energy are necessary to heat the water in the water heater by 25°C

Answer 1

q = mC∆T

q = heat = ?

m = mass of water = 59 gal x 3.785 L / gal x 1000 g / L = 223,315 g = 223.3 kg assuming a density for H2O of 1 g/ml

C = specific heat of water = 4.184 kJ / kg

∆T = change in temperature = 25º

q = (223.3 kg)(4.184 kJ/kg)(25º) = 23,359 kJ

Converting this to kilowatt hours:

23,359 kJ x 1 kWh / 3600 kJ = 6.49 kWh