Saturday, April 7, 2012

Which of these changes involved a physical change and not a chemical change?

In a laboratory experiment, a fermenting aqueous solution of glucose and yeast produces carbon dioxide gas and ethanol. The solution was heated by burning natural gas in a Bunsen burner to distill the ethanol that formed in the flask. During the distillation, the ethanol evaporated and then condensed in the receiving flask. The flame of the burner was kept too close to the bottom of the flask and some of the glucose decomposed into a black carbon deposit on the inside of the flask. During this experiment the following changes occurred.

Check all that apply.
burning of natural gas
formation of ethanol from glucose by yeast
formation of a carbon deposit inside the flask
formation of carbon dioxide gas from glucose
evaporation of ethanol
condensation of ethanol
Correct

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