Question

calculate how much energy is release when 755 grams of copper cools from 125.0C to 19.0C

Answer 1

Solution:

q = C*m*ΔT,

where:

m - mass (kg);

ΔT - change in temperature (°C);

C - specific heat capacity- the energy needed to heat 1kg of a substance by 1°C.

Specific heat capacity of copper = 385 J/(kg °C).

Mass of copper = 755 g = 0.755 kg.

ΔT = (T_{final temperature} - T_{initial temperature}) = (19.0 - 125.0)°C = -106°C.

Therefore:

q = (385 J kg^-1 °C^-1) * (0.755 kg) * (-106°C) = -30811.55 J = -30.8 kJ.

q = -30.8 kJ.

The negative Joule value means heat is being lost.

Answer: q = -30.8 kJ.