CEM131 Lab

We will be doing Lab 8 – Thin Layer Chromatography for lab tomorrow.  Lab6/7 are being redesigned and parts will be used for a handout next week that will be assigned for practice.

CEM131 Grades

The grades for CEM131 are posted for Post Exam 2.  There was a formatting error in the one I showed the morning class which had some grades screwed up.  I have corrected the error, but please double check against your handed back work.

Previous Exams

Wow, looks like a good chunk of people read the exam from last term in CEM131 and used that as study. Here is some advice, I change a significant chunk of questions between terms… And I knew, due to a question a student asked, that the old test was being used… So I made sure a changed almost every question.

Fall 2017 at JC

My son and I with aspirations of a great term approaching.

It is that time of the year when we are all excited and ready to rack up the 4.0 grades, the start of term.

This year is a little bit different for me.  Due to staff retirements and the new HLC (Higher Learning Commission) requirements for highly qualified faculty, I have shifted around my schedule a little.  I will be teaching CEM131 (Introductory Chemistry), CEM241 (Organic Chemistry I), and BIO220 (Introductory Microbiology).  This goes back to my graduate degree in Microbiology and specialization in Bioorganic Chemistry (chemists who take to many biology classes and realize bacteria are better at organic chemistry than me).

Important Dates:

REFUND/DROP NO W BY:  9/14/2017

DROP WITH W BY: 9/15/2017


CEM131 Answers to Questions and the Obvious Thing I Forgot

Here is a copy of the questions from class with the last four answered.

Questions from Class

Now to the second issue, my huge brain fart in class.  I knew when I worked it out (which was about five minutes after the last person left) I would want to bang my head on the board for missing the obvious.  The problem was that we were solving the wrong problem.  The Dilution Equation (C1V1 = C2V2) works when you think about how you made each experiment, not comparing different experiments.  So looking at the second experiment you did, where you made the bleach solution by mixing 5 ml of bleach with 5 ml of water.  Instead of comparing this to experiment one, think about the dilution itself.  C1 = 1.7X10(-4) M, and the V1 = 5 ml (the amount of bleach added), C2 = x, and V2 = 10 ml (the amount of bleach plus the water added).  Solve for C2 = (C1 X V1)/V2 which gives you a concentration half the original.  in the third experiment, change V1 to 2.0 ml and you get 1/5 the original concentration.  I told you it was simple.

I apologize for the brain fart.  Sometimes when you are so used to doing the idea in your head, you forget how to translate it into the math… and this was one of those time.