Lab: Testing Soda Pop for Carbon Dioxide

GRADE SCHOOL LAB
TESTING SODA POP
FOR
CARBON DIOXIDE

INTRODUCTION:

In this lab you will test for the presence of CO₂ gas in soda pop.

MATERIALS NEEDED:

Limewater (See experiment LIMEWATER for instructions.)
Bottle of soda pop (³/₄ full)
Glass
Rubber or plastic tubing
Modeling clay

PROCEDURE:

Take a bottle of soda pop that is about ³/₄ full. Room temperature pop will release the carbon dioxide easier.

Insert one end of your rubber tubing into the opening of the bottle, and seal it in place with modeling clay. Be sure the tubing is well above the level of the pop inside the bottle. See the drawing.

Fill the glass one-half full with limewater, and place the other end of the tubing into the limewater.

Now, carefully and gently, shake the bottle to release the carbon dioxide gas. Don't let it fizz up to the tubing.

Allow the carbon dioxide from the pop bottle to bubble up through the limewater.

Observe the color change in the limewater that shows the gas to be carbon dioxide.

RESULTS:

The limewater turns from clear to a milky color.

Limewater always turns milky when CO₂ is mixed with it. The chemical in the limewater combines with the CO₂ gas in the pop to form a white powder that is not soluble in water. The powder is called limestone. If the solution is allowed to stand for several hours, the powdery limestone will fall to the bottom of the glass.

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