Chemistry                                Quiz #1

 

 

  1. (5 pt)  For each of the following, indicate whether the observed process is a chemical change or a physical change:

 

Ice melts  This is a physical change, you can easily reverse the process by changing the temperature.

 

An egg is cooked  This is mostly a chemical change (this is the hardest one on the quiz).

 

Sugar is consumed for energy   If you are converting sugar into energy, you must be chemically changing it.

 

Gasoline is burned   Chemical

 

Cookie Dough is rolled out   This is a physical change, you can easily ball it up again.

 

 

  1. (5 pt.)  If there are 1.057 quarts in a liter, and 4 quarts in a gallon, and there are two pints in a quart, then how many liters are in a pint?

 

 

 

1 pint *  1 quart  *  1 liter   = 0.473 liters

              2 pints       1.057 qt

 

 

  1. (5 pt.)  To the correct number of significant figures, please tell me how tall I am in meters if I measure myself to be 72.775 inches tall?

[1 inch = 2.54 cm (exactly)]

 

 

72.775 in  *  2.54 cm   *  1 m       = 1.8485 m

                       1 in           100 cm

 

2.54 cm = 1 in and 1 m=100 cm are both EXACT ratios, they have an INFINITE number of sig figs.  So the final answer has 5 sig figs because the original measurement had 5 sig figs.