The definition of a calorie is the amount of energy (heat) toraise 1 g of water by 1 degree C. Here you have 1 liter, which is1000 ml, and if you assume a density of 1g/ml, you have 1000 g ofwater. Thus it will take 1000 calories of energy to raise it 1degree C, which is the same as 1 kcal. In joules, it will be 1000calories x 4.184 joules/calorie = 4184 joules = 4.184 kJ.