Question

En una fundición hay un horno eléctrico con capacidad para fundir totalmente 540 kg de cobre. Si la temperatura inicial del cobre es de 20º C ¿Cuántos kJ de energía calorífica en total se necesitan para fundir el cobre?

Answer 1

Answer:

Q = 2.95*10^5 kJ

Explanation:

In order to calculate the energy required to melt the cooper, you first calculate the energy required to reach the boiling temperature. You use the following formula:

$Q_1=mc(T_b-T_1)$     (1)

m: mass of cooper = 540 kg

c: specific heat of cooper = 390 J/kg°C

Tb: boiling temperature of cooper = 1080°C

T1: initial temperature of cooper = 20°C

You replace the values of the parameters in the equation (1):

$Q_1=(540kg)(390\frac{J}{kg.\°C})(1080\°C-20\°C)=2.23*10^8J$

Next, you calculate the energy required to melt the cooper by using the following formula:

$Q_2=mL_f$         (2)

Lf: melting constant of cooper = 134000J/kg

$Q_2=(540kg)(134000\frac{J}{kg})=7.24*10^7J$

Finally, the total amount of energy required to melt the cooper from a temperature of 20°C is the sum of Q1 and Q2:

$Q=Q_1+Q_2=2.23*10^8J+7.24*10^7J=2.95*10^8J=2.95*10^5kJ$

The total energy required is 2.95*10^5 kJ