Science 8

Mix and Flow of matter

By Rocque Gratix

 

Objectives: Students will learn that gases can be fluid and have varying densities through the investigation of their properties compared to liquids.

 

Lab Activity -- The Carbon Dioxide Extinguisher

 

Materials

1 750ml beaker

1 250ml beaker

1 small tea candle

5 grams of baking soda

5ml of vinegar

1 cardboard lid for the 750ml beaker

 

Procedure

  1. Place the 5g of baking soda into the bottom of the 750ml beaker
  2. Pour the vinegar onto the baking soda
  3. Place the cardboard lid on top of the 750ml beaker to trap the product- CO2 gas
  4. Light the candle and place it at the bottom of the 250ml beaker
  5. Using the spout of the 750ml beaker pour the CO2 gas into the 250ml beaker
  6. Watch the candle extinguish

 

Description

Most students have the misconception that gases are not fluids and cannot be poured this statement is incorrect. In fact gases are fluid and can be poured. In this case we can also show students that gases different densities.  Students will see that the reaction of the vinegar and the baking soda produce CO2 as a product.  Since CO2 (g) is a fluid it can be poured, but it also has a greater density then oxygen O2.  Since the CO2 is heavier than air it sinks below the air and pushes the O2 out of the beaker. When this happens the flame no longer has O2 to fuel the combustion reaction and the candle is extinguished.