7. (20 pts) Unsteady State. In one method of making pickles, cucumbers are soaked in a salty pickling solution that cont

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7 20 Pts Unsteady State In One Method Of Making Pickles Cucumbers Are Soaked In A Salty Pickling Solution That Cont 1 (41.52 KiB) Viewed 40 times

7. (20 pts) Unsteady State. In one method of making pickles, cucumbers are soaked in a salty pickling solution that contains acetic acid at a concentration of 1.6 mol/m! The acetic acid acts as a preservative, and things can be considered "pickled" once the acetic acid concentration reaches 1.568 mol/m'. Consider a cucumber in the pickling process with a radius of 1.5 cm and a length of 18 cm, which is sufficiently long and narrow to consider it a cylinder with negligible diffusion through the ends. Cucumbers do not normally contain any acetic acid (so, CAO = 0) and the diffusion coefficient of acetic acid in water is 3.48 x 10 cm/s. (a) (10 pts) Assuming there is no convection resistance, how long will it take for the concentration to reach 1.568 mol/m' at a depth of 12 cm from the surface of the cylinder? (b) (10 pts) How long will it take for the concentration to reach 1.568 mol/m'at a depth of 0.6 cm from the surface of the cylinder when ke - 2.32 x 10-5 cm/s?