Published : Tuesday, October 7, 2014 | 10:12 PM
A day in the life of a Polytechnic School Chemistry Class:
The goal of the lab is to determine the percentage of copper present in a brass screw. First, the screws react with concentrated nitric acid, forming a toxic brown gas and blue copper ions in solution. Then a colorimeter is used to measure the absorbance of the blue copper ion solution and from that number, students can calculate the concentration of the copper ions. One final series of calculations gets them back to the copper in the brass screw, which turns out to be about 65% by mass.
Polytechnic School, 1030 E. California Blvd., Pasadena, (626) 396-6300 or visit www.polytechnic.org.