This section provides an overview of what happens during a typical laboratory period.

What To Bring

You need to bring all of the following to lab. Failure to bring the following may cause you to be sent out of the lab to get what you are missing with no additional time provided for make-up.

• Safety Goggles: These must cover your eyes completely on all sides. Safety glasses (without protection above the head or on the sides) are not acceptable. These should be worn once you enter the laboratory and should not be taken off until you leave the laboratory or until permitted by your instructor.
• Lab Coat: All students must wear a lab coat throughout the laboratory period.
• Appropriate attire: You should be dressed in appropriate attire when you enter the laboratory as dictated by the safety rules.
  • If it is hot outside, one option is to bring the clothes you need to wear in lab in your book-bag, and then change just before you enter the laboratory. We strongly recommend avoid wearing expensive and/or uncomfortable clothing to the laboratory.
• A Mobile Device: You will use your mobile device to conduct data collection in most experiments.  It is also permissible to use your mobile device to view the lab manual.  The following programs should be installed on your device for data collection:
  • Vernier Graphical Analysis^[1]
  • Vernier Spectral Analysis
• Report Form: Bring a copy of the lab report form.  For many experiments you will be expected to complete this in class.
• Laboratory Notebook: The notebook must have duplicate pages (carbon pages) available on it. While suitable notebooks can be found in the bookstore, you need not use the same brand/exact format of laboratory notebook. If you have remaining pages from another laboratory course from a previous semester, you may reuse this. However, you must use a separate laboratory notebook from any other laboratory course you are taking this semester.
• Pen
• Pencil
• Calculator

In addition, ideally you should bring a hard copy of this manual (including all sections necessary for the experiment at hand, including appendices and the Using Standard Laboratory Equipment section.

Before Lab: Preparing for the Experiment

Before class, please do the following:

Read the Laboratory Manual

Read the entire laboratory write-up, including the report form, carefully. This should explain what you are expected to study in the experiment, as well as what you will do in the experiment.  Where appropriate you should also read the relevant sections of your textbook and/or lecture notes/study guides.

Occasionally, changes to the experiments from the laboratory manual may be posted on Canvas and/or announced at the beginning of the laboratory period.

Make sure that you understand how the experiment works. Specifically, you should not just know what you need to do during the laboratory period. You should be able to answer all of the following questions:

• What is the objective of the experiment?
• How will you measure what you are trying to measure?
• How do you interpret the experimental data?
• What knowledge from your chemistry course do you need in order to finish the lab report? You need to have mastered this knowledge to succeed in the laboratory.
• Can you predict what you are going to see in the experiment?

These will be tested in the pre-lab quiz at the beginning of the lab period.

Notebook Preparation

Before you enter the laboratory, you must write out the purpose and summarize the planned procedure for the experiment in your laboratory notebook. In addition, most students will want to prepare their laboratory notebook to provide a framework for recording the data to be collected in the experiment. This will help you prepare for the pre-lab quiz.  This will be inspected by your instructor at the beginning of the lab period. Points will be deducted if the laboratory notebook is not ready by the beginning of the period.

Please read Keeping a Laboratory Notebook for the expectations

During the Laboratory Period

The primary focus of the laboratory period is to complete the experimental portion. If time is left over, you should complete as much as possible of the laboratory report. Laboratory reports are typically due at the end of the lab period, or at the beginning of the following lab period, as specified in the course syllabus and/or by your instructor.

To prepare you for the lab, you will begin by taking an open-notebook prelab quiz. You will not be allowed to have your lab manual open during this quiz.

Typically, your instructor will then present a brief pre-laboratory talk covering important points about the procedure. However, this briefing typically will only discuss techniques and chemical principles that you may be unfamiliar with as well as key pitfalls in the procedure, as well as changes in the procedure that may have been made. This briefing will not be very useful if you are not fully prepared for the experiment. Nevertheless, you should pay attention to any announcements made, particularly with respect to changes to procedures as well as key tips on how the experiment is performed.

You should pay attention to whether the experiment is performed individually or in groups. Some experiments will be performed in pairs, while others will be performed individually.

After the pre-lab briefing, you will proceed to perform the experiment. Be sure that all procedures are done safely, carefully and efficiently.

Your instructor will circulate to help you with your experiment. In addition, he/she will evaluate your notebook for:

• preparation of the purpose and procedure sections
• recording your data as you go along.

You should feel free to ask your instructor if you have any questions during the experiment – they are here to help.  Points will not be deducted for asking questions. If something goes wrong, your instructor will help you to the best of their ability.

Balances

Balances can easily be made unbalanced and would be even less accurate than before or if chemical residue is left

• Use the paint brushes to brush away stray bits of chemicals on the balance.
• Do not shift or move the balance away from the position.
• If the balance drifts significantly^[2] then you should not fix the balancing yourself: contact your instructor.

Preventing Cross-Contamination of Reagents

It is important for laboratory chemicals to be as uncontaminated as possible. If we aren’t careful, then reagents will be mixed together, and will include other substances which alter the physical and chemical properties of the sample.

For this reason, we must take every step possible to prevent cross-contamination between reagents. There are a few straightforward procedures that you should follow for this reason.

• Tap water should only be used for rough cleaning of glassware, which should always be rinsed with deionized water after use in any event. Otherwise, use deionized water at all times.
• For liquid reagents, never dunk a pipet or another measurement device into the reagent bottle unless one is provided specifically for that bottle. Instead, pour out the amount of reagent needed into a beaker and then pipet the reagent from that.
  • Try and not dispense too much chemical into the beaker; you can always get more if needed from the stock bottle.
  • For most experiments, if you have excess unused reagent in your beaker you should see if other classmates can use it.
• Never pour reagents back into the original reagent bottle, even though it may appear to be completely clean.  Dispose of unused reagent at the end of the experiment as waste.
• For solid reagents, if you must use a spatula, make sure that the spatula is completely clean and dry before placing it into the reagent. After use, wash and dry the spatula before continued use.

Cleaning Up

When the experiment is completed, you will be required to clean up. The laboratory bench should be clear and all reagent bottles must be replaced. Chemicals must be disposed of appropriately.

Waste Generated in the Experiment

All waste – including unused chemicals that you have poured into an alternate container – must be disposed of in the beakers allotted for each type of waste.

• Dirty, non-hazardous solids (paper waste, disposable plastic pipets and plastic cuvettes) should be placed in the trash cans.
• Disposable glass pipets must be placed in the designated box for broken glass. Consult your instructor if it is significantly contaminated with chemicals.
  • Please contact your instructor if you break glassware or otherwise find broken glass. Instructors will be responsible for clearing up broken glass.
• Waste chemicals should be dumped in the appropriate waste beakers provided in the fume hood, unless your instructor informs you that it is safe to pour it down the drain.
  • If you are instructed to pour waste down the drain, be sure to rinse the waste down the drain with copious amounts of tap water.

Glassware

Glassware that was found in your drawer should be washed with soap and rinsed with tap water followed by deionized water. This should then be replaced in the drawer.

Other glassware should, unless directed otherwise, be placed in the dirty glass tray. Follow directions provided for a given experiment after rinsing off as much visible chemical residue as possible.

Other Items

• Replace all other equipment and chemicals to where you originally found it, unless directed otherwise by your instructor.
• Brush off all residue from the balances into a weighing boat gently with a paint brush (found in the wooden box above the tap).
• Wipe down your lab bench with white paper towels and disinfectant (found in red bottles in the wooden box above the sink).

Checking Out of Lab

At the end of the lab period, you will need to be signed out by your instructor. Do not tear out the carbon pages before this is done. Your instructor may grade the notebook on the spot or may assess the notebook based on the carbon copies submitted. After you are signed out, you must detach the yellow duplicate copies of your notebook pages at the front bench before you leave the laboratory, even if these copies have already been graded.

In addition, be sure to turn in the completed short lab report.

Short Laboratory Reports

For most experiments, you will find a report form on Canvas for that experiment.  Complete the report form by answering all questions, being sure to attach graphs and other additional materials as directed on the report form. All answers must be reported with correct units and to the correct number of significant figures.

When asked for sample calculations, you are only required in general to submit one sample calculation if there are multiple trials for which the same calculation is required. However, for all sample calculations, be sure to show all steps in your calculation. When answering questions, make sure that your reasoning is completely explained where appropriate.

Graphing is an aspect of lab reports that causes students difficulties. Some specific guidance on plotting graphs – and expectations in this course related to this – are provided in the Graphing section at the end of the manual.

Unless specifically stated, all calculations and graphs can be completed on the computer (e.g. with Microsoft Excel) or by hand. If you use a computer, you must still print out a copy of the graphs involved on paper.  However, you are encouraged to submit your Excel file via Canvas so that if your instructor believes there is an error they can find it more readily.