What mass of water can be heated from 20 to 50 * C while spending 2520 kJ of energy?

The amount of energy required to heat water can be calculated using the formula:

Q = mc (t1 – t0),

where Q is the amount of heat,

m is the mass of water,

c – heat capacity of water,

t1 – final temperature,

t0 is the initial temperature.

m = Q / c (t1 – t0) = (2.52 * 106 J) / (4200 J / kg * deg * (50 ⁰С – 20 ⁰С)) = 20 kg.

Answer: 20 kg.