How much energy in kilo calorie required to evaporate 1 litter of water?

Answer 1

Water has a high heat of vaporization. At 100 degrees Celsius, it requires about 540 calories to turn one gram of liquid water into steam.

One liter of water has a mass of about 1000 grams. To vaporize 1000 grams of water:

540 calories/gram X 1000 grams = 540,000 calories or 540 Kilocalories.