Problem 1.60 of fundamentals of heat and mass transfer. enhanced etext, 8th edition, by theodore l. bergman; adrienne s. lavine: frank p. incropera: david p. the diameter and surface emissivity of an electrically heated plate are d = 300 mm and c = 0.80, respectively. tood ca d=6,3m (a) estimate the power needed to maintain a surface temperature of 200°c in a room for which the air and the walls are at 25°c. the coefficient characterizing heat transfer by natural convection depends on the surface temperature and, in units of w/ m k, may be approximated by an expression of the form h = 0.80(ts - too) (b) assess the effect of surface temperature on the power requirement, as well as on the relative contributions of convection and radiation to heat transfer from the surface.

the answer would be a

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.