What energy is released during the solidification of 2.5 kg of silver, taken at the melting temperature
What energy is released during the solidification of 2.5 kg of silver, taken at the melting temperature, and its further cooling to 160 degrees?
m = 2.5 kg.
t1 = 960 ° C.
t2 = 160 ° C.
C = 250 J / kg * ° C.
r = 87000 J / kg.
Q -?
The released thermal energy Q can be represented as a sum: the energy Qк, which is released during the crystallization of silver, and its cooling Qо: Q = Qк + Qо.
The crystallization temperature of silver according to the table of crystallization temperatures of substances is t1 = 960 ° C.
Qк = r * m, where r is the specific heat of crystallization of silver, m is the mass of crystallized silver.
The amount of heat Qо, which is released during cooling of silver, can be expressed by the formula:
Qо = C * m * (t1 – t2), where C is the specific heat of silver, t1, t2 are the initial and final temperatures of silver.
Q = r * m + C * m * (t1 – t2) = m * (r + C * (t1 – t2)).
Q = 2.5 kg * (87000 J / kg g + 250 J / kg * ° C * (960 ° C – 160 ° C) = 717500 J.
Answer: when the silver solidifies, Q = 717500 J of thermal energy will be released.
