Procedures: 1. Obtain a thermometer and place it on the bench at your work area.

Question

Procedures: 1. Obtain a thermometer and place it on the bench at your work area. Be careful it does not roll off the bench. 2. Weigh an empty Erlenmeyer flask with a rubber stopper firmly capping it. Record the mass. 3. Place a small piece of solid CO2 (dry ice) in the flask (use about twice the amount you calculated in pre-lab question c). Place the stopper loosely on top of the flask. Watch the flask while the CO2 sublimes. Firmly stopper the flask immediately after all the solid CO2 disappears. 4. Wait until the flask is equilibrated to room temperature (around 5-10 minutes), and then “burp” it by lifting one side of the stopper, and then quickly pushing it back in. This is to ensure that the pressure is the same inside and outside the flask. 5. Dry off any accumulated moisture from the outside of the flask, weigh the stoppered flask (on the same scale) and record the mass. 6. To determine the volume of the flask: fill the flask all the way to the brim with water and stopper it while holding it over a sink. If there is any air trapped inside, try again until only water is present inside the stoppered flask. The volume of the water should be the same as the volume of the air in the stoppered flask. Dry off the outside of the flask completely. Measure the volume of water in a graduated cylinder in batches and add up the volumes to get the total volume of all the water in the flask. Record this as the stoppered flask volume. 7. Read the thermometer in your work area and record the temperature. 8. Read the barometer in the lab and record the pressure in mmHg. Ask me if you need help with the barometer. Don’t forget to correct the barometer reading for room temperature using the table hanging on the wall. Q: Why do we measure the volume of the flask with water rather than using the volume listed on the side?

Explanation / Answer

The readings on the graduated cylinder are higher than the same volume measurement in the Erlenmeyer flask, which makes it more accurate. In a Erlenmeyer flask the larger the volume of the flask, the larger the discrepancy in the volume readings.

Additionally is the phenomenon of formation of meniscus, which makes volume reading difficult, the bigger the mouth of the container, the greater the meniscus and the larger the error.

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.