So you’ll probably use devices that won’t necessarily be the most accurate glassware for measuring volumes in a certain situation. They key to chemistry experiments is to use high-quality products that are tolerable to the hazardous chemicals in use and provide accurate readings.
For over 40 years, Lab Pro has been committed to delivering the most accurate glassware for measuring volume to our customers worldwide. Come visit the biggest Lab Supply showroom in the Bay Area, or contact us online or at 888-452-2776.
In this activity, students employ density calculations to establish the accuracy of several common pieces of laboratory glassware and make a claim relating the accuracy of a piece of glassware to its designated purpose. Accuracy is defined as how close a measurement is to the true or standard value.
Students compare accuracy values for different pieces of glassware using percent error calculations and use percent error as evidence for justifying a claim relating glassware accuracy to use. In this activity, students employ density calculations to establish the accuracy of several common pieces of laboratory glassware and make a claim relating the accuracy of a piece of glassware to its designated purpose.
Accuracy is defined as how close a measurement is to the true or standard value. Students compare accuracy values for different pieces of glassware using percent error calculations and use percent error as evidence for justifying a claim relating glassware accuracy to use.
This quick demonstration is an easy segue into the concept of laboratory glassware accuracy. Obtain dry and liquid kitchen measuring cups.
Determine the percent error in volume for several pieces of laboratory glassware. Make a claim about the acceptable laboratory use of each piece of glassware based on accuracy.
Have a broom, dust pan, and a container for broken glassware available. Remind students not to pick up broken glass with their hands.
Make certain the volume of water the volumetric flask holds will fall between the graduations on the other pieces of glassware. Student: Weigh each piece of glassware and record the mass in table B.
Teacher: Remind students how to read volume-level surface, eye-level, from the bottom of the meniscus. Water from the volumetric flask should be poured into each piece of glassware.
Calculate the group average for the mass of water in each piece of glassware and temperature. Glassware Volume (mL) Volumetric flask 100.0 Graduated cylinder 102.0 Beaker 98.0 Erlenmeyer flask 93.0 Glassware Empty Mass (g)Volume of Water (mL)Mass of Glassware with Water (g)Mass of Water Only (g)Water Temperature © Volumetric flask 65.1100.0164.999.820.0 Graduated cylinder 106.5100.0203.997.420.0 Beaker 169.9100.0266.296.320.0 Erlenmeyer flask 111.5100.0191.879.520.0 Glassware Theoretical Volume of Water (mL)Average Mass of Water (g)Average Water Temperature © Volumetric flask 100.099.520.0 Graduated cylinder 100.097.620.0 Beaker 100.096.320.0 Erlenmeyer flask 100.082.520.0 Based on the data collected, rank the 4 pieces of glassware from most accurate to least accurate.
Student answers will vary, but they should notice higher accuracy for the volumetric flask and graduated cylinder. Average the individual actual volumes for each piece of glassware and place the values in the table.
Glassware Average Actual Volume of Water (mL) Theoretical Volume of Water (mL) Percent Error Volumetric flask 99.7 100.0 0.3% Graduated cylinder 97.8 100.0 2.2% Beaker 96.5 100.0 3.5% Erlenmeyer flask 82.7 100.0 17.4% Calculate the percent error for each piece of glassware and record the values. The volumetric flask had the lowest percent error (0.3%), so it is the most accurate.
The graduated cylinder and beaker were similar in percent error (2.2% and 3.5% respectively). The second method was more precise because volume was calculated using density, the temperature of water, and a digital balance.
Based on accuracy, assign each piece of glassware appropriate uses and state evidence for your choice. If you need to measure other volumes besides those on volumetric flasks, then the graduated cylinder is the best tool.
The beaker is pretty accurate, and you can easily stir and heat chemicals in it. I would not use a flask to measure volume given the large percent error.