Answer to sTEm–at-Work #50: Membrane Technology Decision


Analysis
A technician is involved with the purification step for a drug that uses a membrane to separate the drug from its reaction by-products. The tech understands that the separation is diffusion driven. Thus, after the tech installs the equipment and it begins to operate she knows there will be no drug in the pure liquid at the instant the equipment is turned on.  The process has a sensor in the pure liquid that only monitors the increase in the number of drug molecules as a function of time.  The tech observed the data shown (in the graph below) immediately after the equipment was turned on for the first time.

Usually, the puzzles have a clear yes, or no answer expectation. This is one puzzle that someone can have a Yes answer if the values on the time axis (puzzles usually do not have values on either axis to drive students into "bigger picture" thought processes) are in hours, then a yes argument can be made. However, if we assign a shorter time frame, then the concentration went up way too fast. (There was a hole, or holes in the membrane, or it was not installed properly are better explanations why the "Amount of drug in the pure liquid" is so high so quickly.)  Either way, this a good example of a class time closer where a quick discussion can set the stage to think both ways.                                             

Question: Did the Tech allow the equipment to keep running.  Yes or NO                                                                                                                                                 
Answer: NO