September 2nd, 2014
Pre-Lab 1: Calibration of Volumetric Glassware
The sole objective of this lab is to become acquainted with the scientific techniques that are utilized in this lab including: data analysis, analytical balance, and use of glassware and lab materials. To demonstrate these basic concepts, a 50 mL buret and 10 mL volumetric flask will be calibrated.
Procedure and Equipment:
The following equipment is required to complete the lab:
One 50.00 mL Buret
One 10.00 mL Volumetric Pipet
Scale (preferably stainless steel)
125 mL Erlenmeyer Flask
Safety goggles and glasses
Pen and Notebook
The following procedure must be entertained in order to complete the lab: Calibration of a 10 mL Volumetric Pipet
1). Weigh a 50 mL Erlenmeyer flask. Make sure the glassware is clean and free of any cracks or stars. Also, take note of the temperature of water, as volume varies with temperature 2). Transfer a portion of the water to flask with a pipette and record the mass of flask with the water. Use this data to calculate how much water was transferred from the pipette to the flask. 3). Repeat step two 4 times, ensuring the remaining results are similar to the first trial. Use this data to calculate the mean amount of water transferred and the standard deviation between the data points. Calibration of a 50 mL Buret:
1). Fill the buret with 50 mL of the temperature-equilibrated water. Be as precise as possible in order to obtain reliable data. If the volume changes over a period of a few minutes, obtain a new buret. Be sure to obtain the temperature of the water as well. 2). Weigh a 125 mL Erlenmeyer flask with its stopper. Again, make sure the flask is sanitary and has no cracks or stars. 3). At a rate of 20 mL/min, open the buret stopper and allow 10.00 mL of water to submerge into the flask. Remember to seal off the flask as soon as the water stops in order to minimize evaporation. 4). Using the technique of reading meniscus’s, record the volume reading for the buret to the hundreds place. The last significant digit may be an approximation. 5). Weigh of the stopped Erlenmeyer flask with the water on a scale. Determine the quantity of water transferred from the buret by finding the mass difference from the flask with no water vs. the new weight. 6). Repeat the steps from three to five four more times for the remaining volume of the buret and repeat the whole procedure again with a new 50 mL volume. Remember to record all data. Also, make sure to repeat data that is not duplicated correctly to ensure accurate and precise results. 7). Use the correction data from table one in order to find the true volume of water transferred based on the temperature. Create tables of the recorded data as well as a plot of the correction data with the apparent volume with labeled axis. Perform Calculations 8). Dispose of all glassware and materials accordingly and clean up the lab area. Hazards:
No harmful chemicals will be dealt with in this lab. The only safety hazard is to be cautious of broken or chipped glassware that may cut one’s skin. Make sure to report any mutilated glassware to TA and accidents in the lab must be handled properly.