Question

Discuss at least three sources of systematic experimental error in the distillation, along with their possible implications and effects in the experiment. This discussion of error should be done in some detail. You must cite specific, concrete examples of possible errors and how they will affect the results of your lab. Then, Discuss in detail how you would improve the experiment of distillation itself, or your own performance, in order to minimize the errors you discussed in the second paragraph.

Answer 1

The common errors are

Volume measurements

Leaks

Temperature Measurements

Hydrometer Measurements

Volume measurements: are the most critical part of this technique.

Make sure you read the method for using a volumetric flask correctly.

If you do not have a hot/cold water bath to bring the temperature of the alcohol and the collected distillate up/down to 20 ^oC for an accurate measurement of 250ml, at least make sure that -

• the volume of the wine and diluted distillate is measured accurately by
• using the same volumetric flask
• and measuring both at the same temperature.

Leaks: anywhere in the apparatus, can allow alcohol to escape and be lost through these leaks, giving a false low reading.

• Make sure all joints are secure.
• Make sure that the end of the adaptor receiver protrudes well below the water or distillate in the volumetric receiving flask.

This can best be achieved by attaching a small piece of plastic tubing to the end of the adapter receiver to obtain the appropriate length and to prevent breakage of the bottom of the receiving volumetric flask.

Loss of alcohol: can also occur through evaporation of the warm distillate from the volumetric receiving flask, however, this can be prevented by seating the flask in a cold water bath, packed with ice. Also make sure that an adequate water flow is running through the condenser jacket. Also see leaks.

Measure and record the temperature: of your distillate solution as soon as possible after taking a reading of the apparent solvent concentration with your alcohol hydrometer.

Then apply the appropriate correction from the alcohol-temperature correction table to calculate and record the true alcohol concentration.

Hydrometer measurement errors should also be checked