Chemistry Labs

[mith]

We're going to be doing a bunch of labs in the next 7 weeks, so I thought I'd post here for suggestions... mostly, I'd like you to read over the handouts I'm giving out, and suggest any additional information.

First handout:

Laboratory Information

During the last six weeks, the majority of your grade will be from lab work and reports. Because of safety issues involved, and because several of the labs would be difficult to schedule more than once, I felt I should compile a sheet of information that you will need before the first lab starts.

Safety

Many of the chemicals and instruments we will use in lab can be very dangerous if not treated properly. Because of this, there can be no goofing off in the lab. If you break a safety rule, you will go to the office immediately, and receive a 0 for that lab.

Attached is a sheet of safety rules and information. You and your parent/guardian must sign in order to participate in labs.

Lab Schedule

Some of the labs require most or all of our supply of a chemical, and some chemicals are light sensitive. Due to this, and time constraints, it will be difficult, if not impossible, to schedule make-up labs.

We have checked the schedule for athletic and other events that will take place during the last six weeks, and I have done my best to plan labs for days on which there are no conflicts. Here is the current (tentative) schedule:

Lab 1 – Flame Tests (4-1) –

Lab 2 – Separation of Pen Inks by Paper Chromatography (13-1) –

Lab 3 – Testing Water (14-1) –

Lab 4 – How Much Calcium Carbonate is in an Eggshell? (16-1) –

Lab 5 – Calorimetry and Hess’s Law (17-2) –

Lab 6 – Blueprint Paper (19-1) –

Lab 7 – Casein Glue (21-2) –

I will replace the lowest grade on a lab for the six weeks with a six-weeks test. However, any missed labs after that will be a 0. If there are extenuating circumstances, I need to know about them ASAP, so that we can work out a way for you to make up missed work.

Lab Grade Breakdown

The way I grade labs will vary as you gain experience writing reports. Report writing is perhaps the most important skill you will learn doing labs. You can completely mess up an experiment, but if you can explain why it went wrong and what you could have done differently, you have learned as much or more as if you had done each step correctly.

Grading percentages for individual labs:

Pre-lab – 10%
Laboratory work (participation, safety, teamwork, accuracy of results) – 60% for Lab 1, 50% for Lab 2, 40% for Lab 3, 30% for Labs 4-7.
Laboratory Report (Introduction, Materials, Procedure, Experimental, Data, Results, Conclusion) – 30% for Lab 1, 40% for Lab 2, 50% for Lab 3, 60% for Labs 4-7.

Grading percentages for six weeks:

Each lab – 10% (lowest grade will be replaced by six-weeks test covering all labs, if necessary)
Notebook – 10%
10 Mini-Quizzes – 2% each

Pre-Lab

The week (or a few days) before each lab, we will talk about the concepts involved in class, and I will hand out additional information and the procedure we will use for that lab. On the day of the lab, you are required to show me your pre-lab in your notebook, which consists of a title, purpose, materials, procedure, and a data table (if needed). You will not participate in lab if you have not got your pre-lab finished. If you come to lab with it unfinished, you will lose the pre-lab part of your grade, and will have to hurry to write it so that you can finish the lab before class is over. I know some people are not good at getting things in on time (and I was one of them when I was in high school), but this is very important, and there will be no exceptions.

Lab Reports

Attached is a handout giving guidelines for writing lab reports. We will go over some of it in class, but you are responsible for going over it on your own. As we progress through the six-weeks, we will look at examples of both well-written and poorly written lab reports, and on every lab report you turn in I will mark any areas you need to improve. You should pay close attention to these, and ask me for additional help as necessary. Your report will become a larger and larger part of your grade as we get closer to the end of school, and I will be grading much more closely as well.

Notebooks

Before the first pre-lab, I will purchase notebooks for everyone. Notebooks will be approximately $4 per student. Please bring the money ASAP.

Your notebook will be a major part of your grade. All pre-lab writing should go here, along with your experimental procedure, data, and calculations. You should never write down any measurements or data on a separate sheet of paper, as these are easy to lose. Copies of each lab’s notebook work should be turned in with your lab reports.

In addition, I want you to keep a table of contents at the beginning of the notebook, and a list of chemicals and abbreviations used at the end. We will discuss these in class. At the end of the six-weeks, you will turn in your notebook along with your last lab report, and receive a grade for the notebook as a whole. Do not cram papers (even lab handouts) in your notebook, and take care of it. If you lose it or destroy it, you can purchase a replacement, but you will lose a lot of points for lost work.

I would recommend that you also purchase a small (half inch should be plenty) notebook to keep handouts, quizzes, and lab reports in.

[This message has been edited by mith (edited 03-30-2004 11:24 AM).]

[mith]

Second Handout (coming soon, but suggestions welcome before I type it anyway):

Safety Rules and Guidelines

[mith]

Third Handout (coming soon, but suggestions welcome before I type it anyway):

Writing Lab Reports

[Dragon Phoenix]

I'd definitely include letting them study the material safety data sheets of the chemicals before they handle any.

[mith]

I'm going to include that in both the safety handout and the materials section of the lab report handout.

[Dragon Phoenix]

A bit of a hijack, but never underestimate the stupidity of students in chemistry labs. What I've seen myself:

Example 1:
A student wanted to check whether sodium really reacts violently with water, so he puts a container with water in the fume hood, and drops an egg-size piece of sodium into it. Nothing happens. Puzzled, he removes it from the fumehood, at which point the oil layer that passivied the sodium has diffused away. They had to pick pieces of burning sodium from the ceiling.

Example 2:
A student managed to spill a few liters of ethanol on the floor, and decided to mop it up with towels. Which he then placed on the heaters to dry. No fire fortunately, but everyone in the whole laboratory could go home stone drunk.

Example 3:
A student successfully carried out a synthesis of anhydrous aluminium chloride, with the total exclusion of water (as that reacts violently with AlCl3 to form HCl). After the test is finished, he decides to remove the anhydrous AlCl3 from the equipment by flushing with water. Woosh.

Yup. #3 was DP.

[Quailman]

Until I read that last line I was preparing to ask how old you were when you did each of those.

Another: A student wondered whether the pressure in the water line was greater than the pressure in the gas line, so he hooked each end of a rubber hose to the respective jets. The water pressure was greater. The bunsen burners sputtered for the rest of the term.

[mith]

Fortunately our school is small enough that we can't afford anything *too* dangerous.