A perfect sphere of crystalline sodium chloride salt is stuck at the bottom of a nearly infinite pool of de-ionized water. A distant stir bar is creating an effectively constant velocity profile of 1200 around this crystal (you may assume that the entire crystal is exposed to the water). Calculate the rate of mass dissolution of this 8 mm diameter sphere if the solution is maintained at 20 C and 1200 = 8 %, knowing that: 2 2 615%: = 6-4 M D~a+ = 1.17 =I= 10'5 % pa. = 1.84 a: 10-5 %