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.

Thoughts for Week of April 10th

CEM131: We will be finishing up the Gases chapter this week and starting on Solutions.  The Hardness of Water lab is this week’s lab fun.

BIO220: We will continue with Eukarya pathogens and start Unknowns.  I have posted the current grades, please review missing materials.

BIO161:  We will finish Protostomes on Tuesday and then the Exam on Thursday.  The lab will either be the field hike or dissection, depending on weather.

Musings for the week of April 3rd

General Notes: We are past the last HQV date, so I cannot drop you from the course.  However, if you do not participate (as outlined in the syllabus), you will receive a grade of 0.0 (E) for failure to participate if you do not withdraw before the term deadline.  Several people have received emails this week alerting them to this eventuality.

CEM131: Exam day today, I know, I love it too (come on, only two problems NEED a calculator). Hopefully it wasn’t too traumatic and I plan on getting them graded by Wednesday.  Overall the class is going well and we will start Chapter 7 (Gases) on Wednesday.  The lab will be Lab 11 (Molar Mass of Butane) on Wednesday.

On the labs last week I gave you a plus/minus error of one on the hydration number for Copper (II) Sulfate.  The actual value was five (5) water molecules for each formula unit of Copper (II) Sulfate, so 4-6 were acceptable. Any value above or below that cost you a point (every group was within two), due to sloppy lab technique (resulting in a poor determination).

BIO220: Exam Day on Tuesday, I hope you worked through the Genetics problems… well if you didn’t, I’ll know soon enough.  We also have lab on Tuesday where we will do the second Gram Stain test and the Second Streak Plate Evaluation.  Thursday we will start in Chapter 12, please read through the Fungi section.

I’m finishing up the labs right now, and I must say that I am rather unimpressed with the depth of short answer responses and the quality of mathematical calculations (forgetting to calculate original concentrations from diluted values, medians, etc.).  When I ask you to do some research and compare the behavior of three different microbes in a system, “they are different so they respond differently” is a pretty crappy answer.

BIO161: You guys don’t have an exam this week, but you do owe me a formal lab.  The class will be working on Chapter 34 (Protostomes) this week.  You should be at least through the introduction of the chapter by Tuesday.  We are on track for the next exam to be on schedule (4/13).

The overall grades have been updated and include all materials to this point (yes, even the lab quiz).  Speaking of the lab quiz, the overall median was 17/25 and the high was 22/25, that gave a curve of +2 (took the median to ~74%).

Week 3/27 – 3/30

CEM131: We will be finishing Chapter 6 this week.  I am pushing the exam back to Monday (4/3) so that we can spend a little more time on the calculations.  For lab we will be doing the Stoichiometry of a Hydrate.

BIO220: We will be finishing Chapter 9 and Evolutionary theory on Tuesday and then Chapter 10 on Thursday.  I am pushing the test till Tuesday next week (4/4) so that we don’t have to rush tomorrow.  For lab we will be collecting the plate data, discussing identifications, and working on the Gram Stain and Streak Competencies.  Assignment 1 for the presentation is due this Tuesday (3/28)

BIO161: We have the exam on Tuesday.  The exam will be followed by our first dissection lab and a discussion of the formal lab requirements.  Thursday we will start Chapter 33.

Heat Effect lab Report

A handful of you are emailing me that the link is dead.  It is not dead, you are clicking the wrong link.  It is the Heat Effect lab.  I have checked it on three computers and a number of your colleagues have already turned it in.