Example of Forms of Heat Conductivity

For driving in solids, through the collisions of their molecules produced by those that receive heat directly.
For convection: Ways in which fluids (liquid and gaseous) transmit heat; it is characterized by the rise and fall of molecules.
For radiation: It is the continuous emission of radiant energy from the sun, mainly, and from hot bodies, in the form of electromagnetic waves. In addition to being the ability of a substance to emit radiation when it is hot, it is proportional to its ability to absorb it.
Expression for the amount of heat:
Q = mC_and(T₂ - T₁)
Q = Heat supplied in calories (cal) or (J)
m = Mass of the body in (gr) or (kg)
T₁ = Initial temperature in degrees (° C)
T₂= Final temperature in degrees (° C)
C_and = A different constant for each substance, called specific heat (cal / kg ° C)

EXAMPLE OF A HEAT PROBLEM:

3 kg of ice at -10 ° C will be heated to become steam at a pressure of 1 atm. How much heat is needed?
The necessary heat will be distributed as follows:
1.- Heat to heat the ice from -10 ° C to 0 ° C.

C_and = 0.5 kcal / kg ° C
Q₁= mC_and(T₂ - T₁) = (3 kg) (0.5 kcal / kg ° c) (- 0 ° c - (- 10 ° c)) = 15 kcal
2.- Latent heat to melt it.
latent heat of fusion of ice = 80 kcal / kg ° C
C_F= kcal / kg
Q₂ = mX_F= (3 kg) (80 kcallkg) = 240 kcal
3.- Heat to heat the water obtained from 0 ° C to 100 ° C (C_and = 1 kcal / kg ° C).
Q₃ = mC_and (T₂ - T₁) = (3 kg) (1 kcal / kg) (100 ° C - 0 ° C) = 300 Kcal
4.- Latent heat to evaporate the water.
C_v= 540 kcal / kg
Q4mX_v= (3 kg) (540 kcal / kg) = 1620 kcal
The necessary heat will be the sum of all
Q = Q₁ + Q ₂+ Q₃ + Q₄ = 15 + 240 + 300 + 1620 = 2175 kcal