Safety and Measurement in the Laboratory

 Learning Objectives:

Upon completion of this experiment, students will:

1. 1. (CLO) Analyze evidence to decide if generalizations or conclusions based on the obtained data are warranted 

   2. (CHM 111 MLO1)   Apply units of mass, temperature, time, length, and derived units, such as volume and density using dimensional analysis to solve problems with single or multiple steps or conversions.

      1. Recall the common base SI units of measurement, prefixes, and their associated symbols

   3. (CHM 111 MLO1) Evaluate the uncertainty, accuracy, and precision of measurements.

   4. Use best practices to maintain a safe laboratory environment

   5. Interpret a Safety Data Sheet and chemical hazard label.

   6. Recognize common glassware and equipment used to make measurements with proper significant figures and units

Discussion:

Safety in the laboratory is a priority that everyone must participate in to ensure a fun and fulfilling experience.   The chemistry laboratory is inherently filled with possible dangers.  Equipment, materials, and chemicals all have possible safety concerns.   Every person in the laboratory is responsible for their own safety and for the safety of the group.   Part of having a safe environment is to know the proper use of the chemicals, glassware and equipment and using Good Laboratory Practices which define  a set of principles that define the quality and integrity in data collection and reporting results.  

The proper understanding of the chemicals used in the laboratory is essential.  We need to know how to handle and dispose of the chemical safely.   Safety Data Sheets (SDS) are documents required for specific products by United States Federal Law.  According to federal law, manufacturers and importers of chemical products must produce an SDS for each hazardous chemical they produce or import.    The Safety Data Sheets explain the health, hazards and safe handling of the chemicals used in the lab.  

Chemicals are not the only part of an experiment.  Equipment and glassware must also be used properly to have a safe and productive experience.  Some of the specialized equipment will be explained in the laboratory assignment as needed; however, there are basic techniques in handling, heating and cooling, and measuring that are present in almost every laboratory assignment.   Using tools for measuring volume, mass or temperature, the proper use of the Bunsen burner or a hotplate will be explained in this assignment.    

  Procedure and Reports

Use the following resources to complete the laboratory assignment

If you watched the above video previously, watch these Alternate Safety videos.    All of these must be watched.

• • Flinn Scientific Safety Review:   http://youtu.be/V-fNpaOX0-g

  • Proper Dress and PPE (Personal Protective Equipment) / Lab Safety Video Part 1 - http://youtu.be/GjAD83B4JaY

  • Safety Equipment / Lab Safety Video Part 2 - http://youtu.be/IiHEYtnKfF0

  • Behavior / Lab Safety Video Part 3 - http://youtu.be/e7VkIuiT1kU

  • Chemical Hazards / Lab Safety Video Part 4 - http://youtu.be/8queMM7VVfw

  • Safe Chemical Handling / Lab Safety Video Part 5 - http://youtu.be/uiB8qnlZTAM

  • Other General Hazards / Lab Safety Video Part 6 - http://youtu.be/q8UiamEWz4Q

Complete the Laboratory Safety Agreement and the Laboratory Safety quiz in Canvas after you have watched the ACS Safety video or all of the alternate videos. 

Part II.  Safety Data Sheets and Labels

Read the Experiment 0 document and complete the Part II report sheet below.  

Teachers, students, custodians, and other staff may be exposed to hazardous materials at any time. Such exposure can cause or contribute to serious health effects, such as effects on the nervous systems, kidney or lung damage, sterility, cancer, burns, and rashes. In addition, some hazardous materials may pose immediate physical or chemical risks, such as causing a fire or an explosion. There are three major components to understanding the chemical you will use 

• Labels applied to containers of hazardous materials.  The labels alert the user to the dangers of the product and to the essential precautions for its safe use.

• Safety Data Sheets (SDS) must be prepared by the product supplier and supplied to the user. These sheets provide detailed information about product composition, reactivity, health effects, protective equipment and procedures, and emergency procedures. 

• Education and Training related to hazards and associated safe work procedures is mandatory for those either working with or working in the proximity of the controlled product. 

The American Chemical Society on What is a Safety Data Sheet?  https://www.acs.org/content/acs/en/chemical-safety/basics/safety-data-sheets.html 

Watch the video Chemical Hazards / Lab Safety Video Part 4 - http://youtu.be/8queMM7VVfw    The video talks about the SDS and labeling used for chemicals in the lab, read the discussion in the Laboratory Assignment Part II  and perform the search for the Safety Data Sheet.  

Part III.  Common Laboratory Equipment and THEIR USES

Glassware and equipment is essential to the successful completion of the laboratory assignments.   Part II of this lab focuses on the types of glassware or equipment used in the lab.  

In the laboratory, we use tools, glassware and equipment regularly. The student should be familiar with all the equipment and how to use it properly.   

There are four basic types of measurement we will perform in the lab.

• • mass

  • volume

  • length, and

  • temperature

  • time is a fifth common measurement.  

The equipment and glassware we will use in the lab to make these measurements is described in the laboratory assignment beginning on page 15.  There are many assessments and resources online to help you identify the glassware and equipment we will be using in the laboratory, this is one you can use to help identify different equipment or glassware.

• http://www.sciencegeek.net/Chemistry/taters/labequipment.htm

Part IV.   Use of Tools to make Measurements

The portion of the experiment will be completed in the laboratory.   The report sheet must be completed using the data collected by the student.  

Measurement in the laboratory is how we collect data. The tools we use have defined precision based upon the scale represented on the tool. To be able to read the tool with the proper precision, the student must understand the scale. Unit also provide information about the measurement, no number should be represented without a description or a unit. 

When a tool is used the ability to make the measurement is dependent upon  the markings or scale used on the tool.  Precision of the measurement is indicated by the number of values or decimal places that can be represented by the scale of the tool.  

Mass:   

Using a single object, weigh the object on 4 different balances, Determine the average and average deviation of the four masses. Consider: Are all the masses the same? Why are there differences? A balance has precision based upon the number of decimal places it displays for the mass, but the precision of the mass is determined by the average deviation which shows how close each mass is to the average value or to each other. 

The proper use of the analytical balance will be described by your instructor.  Every balance should always be left clean, any materials spilled wiped up.   The doors on an analytical balance should be closed during and after your measurement.   Obtain an object and measure the mass on each of the analytical or pan balances provided.   Report the mass to the proper significant figures.    Compare the mass taken on each balance; calculate a mean or average mass and the standard deviation.  Report the answer to the proper significant figures.

We use balances to determine the mass.  The following videos show the proper use of an Analytical Balance:  

• • • https://youtu.be/Q54u7K7x9-o?list=PL967C03F996296203

    • https://youtu.be/dNeNBx8nAyQ

Volume:   

We will determine the volume of liquid in several different glassware items.  We tend the measure volume in volumetric glassware that gives a higher degree of precision or significant figures.   These include graduated cylinders, volumetric or graduated pipets and burets.   We never use beakers or flasks to measure precise volumes, the error is too great for a good measurement.   

Record each volume measurement with the correct number of significant figures and units. Remember to observe the water level at eye level

Volume measurements use various tools, but to make precise measurements we use the following tools.  

• • • Using a Buret or a pipet:  https://youtu.be/Asg55fFt4zk

    • how to read a graduated cylinder:  https://youtu.be/7ewRaV5baik

    • Buret Tutorial:  https://drive.google.com/open?id=1RgFQPJyeiAMbCiXRn21_U2X2XpeKyyqWDHVzVts2As

Practice of reading volume:     In this simulation (https://teachchemistry.org/classroom-resources/measuring-volume-simulation), students will participate in a 10 question quiz. The quiz questions are each made of two parts, with the first part requiring the student to analyze an image of a graduated cylinder in order to report an accurate measurement. Students must use the correct number of significant digits based on the markings presented on the cylinder when reporting the measurement. In the second portion of the question the students will determine the uncertainty value of the graduated cylinder, again by analyzing its markings. The simulation is made up of several different sizes of graduated cylinders, each containing unique markings, so students will be challenged to analyze each individually. 

Length:  

Measurement of length can be accomplished using several tools.  

• • How to read a metric ruler:  https://youtu.be/GbOu0d18mSg

  • How to read a micrometer:  https://youtu.be/O8vMFFYNIfo

  • How to read a caliper: https://youtu.be/MHu_BaYoKfM 

Temperature: 

• • We can use several types of thermometers, digital, mercury or alcohol thermometers.  

  • Most thermometers that we have in the lab can often read temperature in both the Celsius or the Fahrenheit scales but generally, we always use the Celsius scale in science.   

  • Using the Fahrenheit scale, measure the temperature of water in a beaker using a thermometer.  

  • Convert the measured temperature into Celsius.   Always show your work and the equation used to calculate the value.

  • The third temperature scale we use in science is Kelvin.   The Kelvin scale or Absolute temperature measures the energy of the particles and becomes extremely important when we are looking at the atomic scale of matter.  Convert the measured temperature into Kelvin.