An Introduction to Lab Procedure
To obtain a higher understanding of lab techniques.
Procedure Part A
1- Draw about 400 mL of deionized water into a clean beaker, and let it stand for 15 minutes to equilibrate to room temperature. Note, there is only one deionized water tap in the lab room; make sure you use the correct tap. 2- Confirm that your 10.00 mL volumetric pipet is clean by filling to above the mark with deionized water and then letting it drain. Your pipet is a transfer pipet is a transfer pipet that is calibrated “to deliver” (TD) rather than “to contain” (TC). The last drop of liquid should not drain out of the tip of a TD pipet in normal use. However, there should be no water drops left on the side walls. The presence of such drops indicates that your pipet is dirty. 3- Measure and record the mass of a clean 126 mL. Erlenmeyer flask. 4- Measure and record the temperature of the room and of the water that was set aside in step 1. The two temperatures should agree before you continue. Read the thermometer to the closest one tenth of a degree, using your best estimate. Please be especially careful with the thermometer. 5- Use your pipet to deliver 10.00 mL of the equilibrated water into the Erlenmeyer flask. Note the precision used here. 6- Measure and record the mass of the flask and the water. 7- Repeat steps 5 and 6 at least two additional times without emptying out your flask between trials. 8- Calculate the mass of water delivered by your pipet for each trial. Use your mass of water and the volume of the volumetric pipet to calculate the density of water for each trial. Calculate the average density, standard deviation, and the 90% confidence limits for the average density. 9- Use the temperature of your water along with the values of mass and volume of water given in Table I to calculate the accepted values for the density of water. 10- Determine the relative error with respect to the average density of water. The relative error is defined by: Relative Error= Experimental result-accepted value/Accepted Value X 100
| 84.45 g
| 93.72 g
| 102.7 g
| 112.5 g
Average Experimental Density= 0.985 g/mL
Accepted Density= 0.996 g/mL
Standard Deviation= 0.0057
Relative Error= 6.12%
Confidence limit= 93.88%
Procedure: Part B
1. Discard the water in your Erlenmeyer flask, and re-measure the mass of the flask. The inside of the flask need not be completely dry because any water left in it is from the previous procedure and is at the same temperature as the new water you will be adding. 2. Use a 50 mL buret and accurately measure out about 24mL of room temperature deionized water from part A into the flask. You should read the buret to the closest one hundredth mL. In your laboratory notebook, record your initial buret reading and your final buret reading. The volume of water delivered by the buret is the difference between the final and initial buret reading. 3. Measure and record the mass of the flask and the water. 4. Repeat steps 2 and 3 at least two additional times without emptying out your flask between trails. 5. Calculate the mass of water delivered by your buret for each trial. Use your mass of water and the volume of the water delivered by your buret to calculate the density of water for each trial. Calculate the average density, standard deviation, and the 90% confidence limits for the average density. 6. Assuming that the water temperature has not changed, compare your experimental value of the density of water to the accepted value of the density of water you calculated in part A 7. Determine the relative error with respect to the average density of water when measured by the buret.
Average Density- 1.039g/mL
Procedure: Part C
1. Measure and record the mass of clean and dry 100 or...
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