DENSITY OF ANTIFREEZE- WATER MIXTURES
In this experiment, several mixtures of water and ethylene glycol (the major component of ‘’antifreeze’’) will be prepared and their densities measured. A calibration curve will be generated by plotting density versus percent antifreeze, and this curve will be used to determine the composition of an ‘’unknown’’ sample mixture.
WARNING: ethylene glycol major component of antifreeze is a sweet tasting, poisonous liquid. Avoid unintentional ingestion by following standard laboratory safety measures.
Step 1using a clean 10-ml pipet, transfer precisely 4.00, 3.50, 3.00, 2.50, and 2.00 ml of tap water to five separate test tubes.
Step2: after rinsing the pipet with a small quantity of antifreeze, transfer precisely 1.00, 1.50, 2.00, 2.50, and 3.00 ml of antifreeze to the 70-mm test tubes to give a total added volume of 5.00 ml in each tube.
Step3: stir up each tube to ensure methodical mixing of the liquids. The resultant mixtures are normally 20, 30, 40, 50, and 60% antifreeze by volume, respectively.
Step4: weigh a precisely measured volume (ca. 3ml) of each of the five samples by first rinsing the pipet with a small portion (ca. 1ml) of the sample and then transferring the precisely aliquot to a preweighed beaker.
Note: the weighing vessel needs not to be emptied after each addition; the mass of each aliquot is given by the difference in the mass of the beaker and its contents before and after addition of the aliquot. For best results, perform all weighing in an uninterrupted sequence on the same balance.
Step5: weigh a precisely measured volume (ca. 3ml) of an antifreeze/water mixture of ‘’unknown’’ composition provided by the instructor.
Use the mass and volume data to calculate densities for the five standard samples and the unknown sample. On graph paper, plot mixture density versus % antifreeze for the standard samples. Draw the...