A mosquito fumigator is designed to deliver a nerve vapor, just to kill mosquitos. The device consist of 10cmx10cm in area and 0.5 cm in thickness as a square gel mat. A heating element in the bottom of the mat maintains a constant surface temperature of 50°C to evaporate the nerve substance. Air at 25°C flows parallel to the mat at a velocity of 0.2 m/s, and nerve vapors are immediately diluted to a very low concentration. The density of the gel is 1.1 g/cm3, and the initial loading of the nerve compound is the solid is 25 mol %. The diffusion coefficient of the volatile substance generating the nerve vapor is 0.085 cm²/s in air at 50°C. The vapor pressure of this substance is 500 Pa at 50°C, and its molecular weight is 120 g/gmol. Assume that the release of the nerve compound is controlled by convective transport across the gas film surrounding the mat and the size of the mat remains constant. Neglect the internal diffusion of the nerve substance within the mat itself and side-edge effects. (1) Determine the value of the mass-transfer coefficient at the center of the mat plate. (2) What is the initial rate of nerve vapor delivery to the surrounding in grams/hour? (3) How long can the gel mat provide nerve vapor?