Air at 100 c flows across a thin, flat plate of subliming naphthalene that is 3.4 m long. the reynolds number at the trailing edge of the plate is at the upper limit for a laminar boundary layer (re 5e5). estimate: (a) the average rate of sublimation in kmol/s*m2; and (b) the local rate of sublimation 0.5 m from the leading edge. vapor pressure of naphthalene = 10 torr viscosity of air 0.0215 cp; molar density of air 0.0490 kmol/m3; and diffusivity of naphthalene in air = 0.94x10-5 m2/s

answer: the rate of diffusion increases with increase in temperature.

increase in temperature, increases the molecular/particles speed (kinetic energy. diffusion means movement of particles through the material.

generally, the heavier the particle the more it interacts with the environment and more the temperature matters. so higher temperature results in higher diffusion.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.