BackCHEM 109L Laboratory Safety, Integrity, and Measurement Techniques – Study Notes
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Laboratory Safety and Rules
Condensed Laboratory Safety Rules
Laboratory safety is essential for accident-free operations in chemistry labs. Strict adherence to safety protocols protects students and staff from chemical hazards and physical injury.
Wear safety goggles at all times in the laboratory. Never wear contact lenses in the lab due to risk of chemical exposure.
Horseplay is strictly prohibited to prevent accidents.
Unsupervised work is forbidden. Always work under instructor supervision.
Report all accidents immediately to your instructor.
Know the location of safety equipment: fire extinguishers, eyewash stations, safety showers.
Handle chemicals with respect. Be familiar with their properties and hazards before use.
Handle glassware carefully to avoid breakage and injury.
Wear proper clothing. Bare feet and open-toed shoes are not permitted.
Never light a flame until you are sure there are no flammable materials nearby. No smoking is permitted.
Maintain neatness to reduce accidents. Clean up spilled chemicals, broken glass, and floods immediately.
Think! A conscientious and scholarly attitude is the best defense against laboratory accidents.
Example: If a chemical spill occurs, immediately alert your instructor and use the appropriate spill kit to clean up, following all safety procedures.
Special Health Considerations
Certain health conditions may increase susceptibility to chemical hazards. Students with the following should consult the instructor or safety committee:
Pregnancy
Chronic breathing problems (e.g., asthma, emphysema)
Immune suppression (e.g., organ transplant, AIDS)
Chronic anemia
Example: A student with asthma should avoid exposure to strong fumes and work in a well-ventilated area.
Academic Integrity in the Laboratory
Principles and Policies
Academic integrity is fundamental in all aspects of student work, including examinations, laboratory reports, and assignments. Plagiarism, falsification of data, and copying are considered serious violations.
Plagiarism is presenting someone else's work or ideas as your own, whether from print or electronic sources.
Cheating includes copying reports, falsifying data, and unauthorized collaboration.
Students must read and understand the university's full plagiarism policy.
Instructors have the right to use electronic tools to detect plagiarism.
Example: Copying another student's lab report is considered academic dishonesty and may result in disciplinary action.
General Laboratory Instructions
Required Materials
Students must bring the following to each laboratory session:
Lab coat
Safety goggles
Bound laboratory notebook (spiral notebooks are not acceptable)
Calculator
Example: A student who forgets their safety goggles will not be permitted to participate in the lab.
Laboratory Notebook Guidelines
The laboratory notebook is a permanent record of your work. Each experiment should begin on a new page and include:
Title of experiment
Purpose of experiment
List of materials
Brief outline of procedure
Blank data tables
Any calculations or observations performed before the lab
Example: Before starting an experiment on density, prepare a table for mass and volume measurements in your notebook.
Laboratory Session and Reporting
Record all observations and data in ink as the experiment proceeds.
Laboratory sessions are typically 2 hours and 30 minutes long.
Complete all calculations and draw graphs on suitable graph paper.
Discussion of results should be included in the notebook.
Example: After measuring the temperature change in a calorimetry experiment, graph the data and discuss possible sources of error.
Basic Measurement Techniques
Introduction to the Metric System
The International System of Measurement (SI) is the standard for scientific measurement. It uses base units and prefixes to express quantities.
Metric Prefix | Abbreviation | Multiplier |
|---|---|---|
mega- | M | |
kilo- | k | |
centi- | c | |
milli- | m |
Example: 1 kilometer (km) = meters (m); 1 milliliter (mL) = liters (L).
Estimating and Uncertainty in Measurement
All scientific measurements include some uncertainty. The last digit in a measurement is the estimated digit, representing the uncertainty.
When reading analog devices, estimate one digit beyond the smallest scale division.
Uncertainty depends on the measuring device:
Measuring Device | Uncertainty |
|---|---|
10 mL graduated cylinder | mL |
50 mL graduated cylinder | mL |
50 mL buret | mL |
Example: If you measure 7.25 mL in a 10 mL graduated cylinder, the uncertainty is mL.
Significant Figures
Significant figures reflect the precision of a measurement. The number of significant figures is determined by the measuring instrument and estimation.
All nonzero digits are significant.
Zeros between nonzero digits are significant.
Leading zeros are not significant; trailing zeros in a decimal number are significant.
Example: The measurement 0.0450 g has three significant figures.
Basic Measurement Calculations
Common calculations in the laboratory include density, specific gravity, and solution concentration.
Density is mass per unit volume:
Specific gravity is the ratio of the density of a substance to the density of water:
Solution concentration (molarity):
Example: If a solution contains 0.5 moles of NaCl in 1.0 L of water, its molarity is M.
Additional info:
These notes are based on the CHEM 109L laboratory manual, which covers foundational laboratory safety, academic integrity, and measurement techniques essential for GOB Chemistry students.
Further topics such as calorimetry, synthesis and analysis of aspirin, alcohols, phenols, esters, carbohydrates, solubility, acids and bases, and amino acids/proteins are listed in the table of contents and are covered in later sections of the manual.
