Question

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. Which of these changes involved a physical change and not a chemical change? Check all that apply. Check all that apply.

1-condensation of ethanol

2-evaporation of ethanol

3- formation of carbon dioxide gas from glucose burning of natural gas

4-formation of ethanol from glucose by yeast

5-formation of a carbon deposit inside the flask

Answer 1

1-condensation of ethanol

2-evaporation of ethanol

Explanation:

According to the question ,

• As the compound condenses , it is a basic process of the change in the state , and hence , it is only a physical change .

• Then , the ethanol is changing its state, hence , again a physical change is observed .

• The carbon dioxide gas is formed from the glucose would be a chemical change since a new product is formed i.e carbon dioxide , from the reaction between the glucose and yeast .

• The formation of a carbon deposit was due to the heat which altered the chemical make - up of the substance and is therefore a chemical change .