Introduction

1. Introduction Welcome to CHEM 162 Brendan Stamper brendan.stamper@seattlecolleges.edu 206.683.1139

2. Outline • Go over syllabus • Introduction to lab section • Start chapter 10 • Discuss chapter 10 project

3. Lab overview • Held on Wednesdays (typically the last 2-3 hours of class) • Lab attendance is mandatory and there are no make up labs • Please contact me if you miss a lab due to illness or some other emergency. We can work something out but it will not be for full credit since part of the credit is actually doing the lab • Things to consider • Most of the labs take about 90 minutes • While a few do require more time, it will take more time if you do not come prepared • Patience and attention to detail will help you do well in the lab • There are 8 graded labs, each consisting of . . . • Preparation (prelab) work • Lab work • Postlab work

4. Prelab • Grading prep work • I will have a checklist and check your notebook at the start of class • Necessary information should be filled out before class begins and must be signed off by the instructor before you start working (more on this later) • If I see you doing pre-lab work in lab (i.e. not done before you get here) you will not get credit • Do not start early • The first 5-10 minutes are for me to provide useful hints and information • If you’re setting up, you’re not paying attention

5. During lab • No food or drinks, ever • Personal items should be stored underneath bench-tops • Protective eyewear should be worn at all times until everyone is done (or I say so) • Wearing them on your neck, on your forehead, on your hair, or putting them on the bench does not count as wearing them • They may be uncomfortable, leave marks, and look funny, but the alternative is blindness. So keep…them…on! • One reminder is all I will give. After that, you will lose points each time I see it

6. Postlab • You are welcome (and I encourage you) to stay when you are done • Work on calculations • Calculations should always include correct significant figures and units • You need to show one sample for each different type of calculation • If you repeat a calculation two or three times you do not need to show the work for every individual calculation (unless you want to) • Ask questions • Check answers • Before you leave, show me your notebook (~5 points) • I will have a checklist and check your notebook at the end of class • Coming back after class does not count because I don’t know if you actually did it or just copied it • Necessary information should be filled out before leaving (i.e. calculations, tables and figures)

7. Grading The lab section is worth 120 out of the total 460 points for the class (~25%) Lab work 80 points 10 points per lab Lab reports 40 points 5 points per report

8. Lab work grade breakdown • Prelab (~5 points) • Name/date/lab name • Answers to pre-lab questions (if any) • Purpose or objective of the lab • Summary of the procedures (at least one high quality paragraph outlining the lab) • During lab • Points will be deducted for not following safety rules and lab practices (e.g. -2 points for not wearing proper attire) • Post lab (~5 points) • Notebooks will be checked for the following: • Sig figs and units • Completed data tables • Calculations (show work for credit) • Completed postlab questions • Points will be deducted for not cleaning your bench or shared workspaces

9. Lab report grade breakdown • Lab reports are due at the next lab meeting (typically one week) • They are due at the start of class • One lab report per group • 5 points per report • 1 point for the Abstract • 1 point for the Introduction & Methods sections • 1 point for the Results section • 1 point for the Discussion section • 1 point for overall report

10. More on the lab notebook:General information • You may use any notebook you like (carbon pages are not required) as long as it is • Dedicated to lab (not in your normal note-taking notebooks) • Bound (absolutely no loose pages) • If it meets the above specifications, feel free to use the same notebook you used in CHEM161 • The notebook is your record of what you did and what you observed • Never, ever, ever write anything on scrap paper or the lab handouts. Everything goes into the notebook

11. More on lab notebook:Procedure summary • This prelab component not only helps you prepare for the lab, but also gives you a head start on the methods section of your lab report • Sample full credit procedure summary (shows you read and understand the lab): “In this lab we will do four different acid-base titrations: strong/strong, strong acid/weak base, strong base/weak acid, and weak/weak. First, we will set up the titration apparatus and prepare the LabPros to collect titration data. Next, we will measure the volume of an individual drop from the burette. Finally, we will carry out the four titrations using different combinations of acids and bases and record the titration curves using the LabPro. After the titrations are done, we will dispose of the waste products in the appropriate container.” • Sample zero credit summary: “We will do lots of different titrations.”

12. Precision vs Accuracy • Precision • reproducibility or repeatability • Accuracy • degree of closeness of a measured value to its actual value (i.e. getting the “right” answer) • Data may be • Precise, but not accurate (good, not great) • Precise and accurate (best) • Not precise and not accurate (worst) • In general, precision is more important than accuracy • Accuracy problems can be fixed (calibrations, changes to method, etc) • Precision problems can be difficult to track down and fix