Molten lead weighing 100 g solidifies and cools down to a temperature of 27 C

Molten lead weighing 100 g solidifies and cools down to a temperature of 27 C. How much heat does lead transfer to surrounding bodies? The melting point of lead is 327 C.

To calculate the heat transferred by lead to the surrounding bodies, we will use the formula: Q = λ * m + Cc * m * (tpl – t) = m * (λ + Cc * (tpl – t)).

Variables and constants: m is the mass of lead (m = 100 g = 0.1 kg); λ – specific heat of crystallization of lead (λ = 0.25 * 10 ^ 5 J / kg); Cc is the specific heat of lead (Cc = 140 J / (kg * K)); tmelt – melting point (tm = 327 ºС); t – final temperature (t = 27 ºС).

Calculation: Q = 0.1 * (0.25 * 10 ^ 5 + 140 * (327 – 27)) = 6.7 * 10 ^ 3 J (6.7 kJ).