The amount of heat that needs to be absorbed by a certain mass of water is calculated through the equation,
H = mcpdT
where m is mass, cp is specific heat, and dT is temperature difference.
H = (15.5 g)(4.184 J/g°C)(50°C - 20°C)
H = 1945.56 J
Thus, the amount of heat that needs to be absorbed is 1945.56 J.
