Aclosed box is filled with dry ice at a temperature of -94.7°c, while the outside temperature is 26.8°c. the box is cubical, measuring 0.285 m on a side, and the thickness of the walls is 3.75 x 10^-2 m. in one day, 3.64 x 10^6 j of heat is conducted through the six walls. find the thermal conductivity of the material from which the box is made.

Explanation:

3.64 x 10⁶ J passes through 6 walls

heat energy passing through 1 wall = 0.606 x 10⁶ J

Surface Area of 1 wall A = .285² = 0.081225 m²

Temperature Difference = T₁ - T₂ = 26.8 + 94.7 = 121.5

Thickness of wall d = 3.75 x 10⁻² m

Rate of heat flow per second R =

=7.01 J per s.

Formula for rate of heat flow

R =

Where K is thermal conductivity.

7.01 =

K = 2.66 X 10⁻² W m⁻¹s⁻¹

freezing

deposition

condensation

explanation;

melting also called fusion is the process where solid becomes liquid, sublimation is the process where solid becomes gaseous without first changing to liquid, deposition involves change from gaseous to solid state, freezing involves change from liquid to solid, boiling or evaporation involves change of liquid to gaseous state, while condensation is the change from gaseous state to liquid state.

endothermic reactions involves absorption of heat from the surroundings or the environment while exothermic reactions involves loss of heat energy to the surroundings.

in this case, sublimation, evaporation and melting are endothermic reactions (gain energy from the environment) while, freezing, deposition and condensation are exothermic (loss of energy to the surroundings) reactions.