AP Chemistry Labs

1. AP Chemistry Labs Do Now: Study for Lab Safety Quiz Now Playing: Weird Science by Oingo Boingo

2. Lab Portion of AP Chem • The College Board requires that students spend at least 100 minutes a week in a laboratory environment and develop skills in scientific writing. • Science or technical writing is much different than writing for a Literature or Social Science class. • Technical writing is about efficiency and objectivity. • The more “opinion” you put into a scientific work, the less credible you sound. You want to sound like a textbook. • These skills take lots of practice. • It is likely that your first lab report will be terrible. That’s OK. Keep improving, and you will do just fine at the end of the course.

3. AP Chem Labs • You will be performing 20 college-level experiments, with topics chosen mostly by two criteria: • How relevant is it to the AP curriculum? • How valuable will these skills be in college science in general? • With these in mind, I have chosen to place a definite focus on making sure you get great experience in the following: • A wide variety of experimental methods • Titrations (probably the second most common technique) • Solution making (the most common technique) • Usually, you will have two double-lab days to perform a lab • Day 1 – Perform the lab • Day 2 – Continue working if necessary, lab carts will be in the room for you to work on the lab report.

4. Equipment • You may leave and enter the prep room at your leisure. This means I place a lot of trust in you. In the prep room, you will find: • Analytical balances – I have two that will turn on, and one that I’m trying to get repaired. One is fairly reliable, but you have to make sure the doors are shut. • Meker burners – more even heating elements • Larger beakers and graduated cylinders, in case you need to make a large volume of something. • Centrifuge and spectrophotometer • If you need to work on a lab while I am teaching another class, you may do solution prep and massing in the prep room.

5. Lab Procedures • You will be working with a single lab partner (group of two) for most labs. For some experiments, a group of four is necessary. • You will know what experiment you will be doing ahead of time. You must come prepared to lab having read the lab procedure ahead of time, so that you have an idea as to what you will be doing that day. I will clarify procedures, of course, but most lab errors come from not reading the procedures carefully.

6. Lab Procedures • You will be working with a single lab partner (group of two) for most labs. For some experiments, a group of four is necessary. You may use all lab tables except the small one near the door. • You will know what experiment you will be doing ahead of time. You must come prepared to lab having read the lab procedure ahead of time, so that you have an idea as to what you will be doing that day. I will clarify procedures, of course, but most lab errors come from not reading the procedures carefully.

7. The Lab Report • All labs will be word-processed. No exceptions. If you do not have a computer, please make arrangements to use someone else’s and work ahead of time. • Each lab report will be worth 50 points (half a test grade) • You must submit your lab reports by 3:30 on the due date, or else you will lose 5 expectations points. If you are over 24 hours late, you receive a zero. • You may e-mail your reports as long as they are submitted via PDF or Microsoft Word (.doc or .docx). If it is a different format, I will not accept it and the clock will continue ticking. • If you have a true emergency (death in the family, serious sickness, etc,) let me know ASAP so we can make arrangements, otherwise follow the syllabus guidelines. • If you are absent for one day on the due date, I still expect the lab report at 3:30 in my e-mail. For better or worse, these absences tend to be strategic in nature.

8. Scientific Writing • Cut the crap. There’s no length requirement, so don’t pretend this is your Lit research paper and repeat yourself. • Bad: First, we got out a graduated cylinder. Then, we added 100 milliliters of distilled water. We dumped this in a 100 mL beaker and added one mole of pretty blue copper (II) nitrate crystals. We then took out a glass stirring rod and stirred until the crystals were completely dissolved. We then put it into an Erlenmeyer flask and labelled it as 0.1 molar copper (II) nitrate. • Good: 100 mL of a 0.1 M solution of copper (II) nitrate was prepared. • Can a competent scientist repeat the experiment based on your explanation? In this case, it is reasonable to assume that a scientist knows how to make a solution, and you don’t have to explain the whole process.

9. Section 1 – Objective (5 pts) • What was the point of the experiment? It’s okay for this to be obvious – there doesn’t need to be a “greater meaning of life” attached to this. • Last year – titration experiment • Objective: The objective of this experiment was to determine the concentration of an unknown solution of NaOH through titration with HCl. • Don’t do this: The objective of this experiment was to learn about titrations so that we can become better lab students.

10. Section 2 – Procedure (10 pts) • Again, don’t make me read volumes. Keep it short and to the point. This is a summary of the procedure, so that a scientist can repeat your experiment. Do not simply recopy it. No lists! • If I have to sludge through your lab report, I get angry and take off points.

11. Section 3 – Data & Results (10) • Data – raw numbers taken from instruments or equipment. • Results – as soon as you touch data with math, it becomes a result. • You can combine these if you want, or you can keep them separate. Just don’t mislabel them. • Use tables to organize data. Make sure you label your tables in numerical order, and that each table has a title. (Ex. Table 1: Mass and Volume Data)

12. Section 4 – Graphs (5) • I prefer that you use Microsoft Excel or similar spreadsheet software for these. If you need training on using Excel, we will have lab carts in the room on our second lab day so that I can help walk you through it. • Good graph elements: • Appropriate scale & title • Labeled axes with units • Neatness & accuracy • Line or curve of best fit • Equation of the line (you do not have to do a regression of non-linear functions like parabolas or rational curves)

13. Section 4 – Graphs (5)

14. Section 5 – Sample Calculations (5) • This is the only element of the lab report that can be handwritten. • For each “type” of calculation you do, you need to provide an example of it, and cite it in the lab report. • Ex. Density of lead = 3.4 g/cm3 (SC 1) • Please don’t do this for every example – I won’t read it, and will be angry that you wasted trees.

15. Section 6 – Questions (10) • Answer the questions to the lab here. You only have to provide the answers – calculations should go in the Sample Calculations. • How I grade these: I use an Excel spreadsheet and plug your numbers into my formulas on Excel to check your accuracy. • I provide work space in the lab manual, but I am only interested in the lab report. Do not turn in the lab. That goes with you to college.

16. Section 7 – Conclusion (5) • This is the hardest section to write. In Lit, you’re taught to end with a bang or some grand thought. I’m not interested in that. • State whether or not the objective was met. Read the objective before writing – I have read countless lab reports where the conclusion is not related to the objective, which is just silly. • If the objective was to find a particular value, restate the value. • Mention sources of error.

17. Section 7 – Conclusion (5) • “According to the experimental data and results, the concentration of the unknown NaOH solution was 1.05 M. Based on the actual value of 1.00 M, the percent error was 5%, potentially caused by inexact buret readings. Due to the low percent error and successful titration, the objective of the experiment was met.” • Done. Step away from the paper. There’s nothing to see here. You’re done. Do not tell me how you are a better person for having done this titration, or how pretty the phenolpthalein looked… just stop writing.