How much heat in kcal must be added to 0.5kg of water at room temperature (20°C) to raise its temperature to 50°C?

We know that the energy required to raise the temperature of a substance is the product of that substance's mass, specific heat capacity and the change in temperature. Mathematically:

Q = m * Cp * delta (T)

The Cp of water in Kcal / (kg*K) or Kcal / (kg*C) is 1. (Per unit Celsius and per unit Kelvin are interchangeable because one degree change in Celsius is equal to one degree change in Kelvin)

Using the formula,

Q = 0.5 * 1 * (50-20)

Q = 15 Kcal