Good news and the bad news about elevated CO2 levels in the atmosphere. –Good news: The ocean is absorbing a good deal of this CO2, therefore slowing global warming. –Bad news: As the excess CO2 dissolves in the ocean, the ocean becomes more acidic therefore threatening marine life that uses calcium carbonate to build its skeleton or shell. Think of coral, lobsters, star fish, and mollusks.

In experiment #2, we showed that CO2 comes from car exhaust as the engine burns gasoline making CO2 and water. When CO2 dissolves in water, we showed that it becomes carbonic acid. This acid is what threatens the marine animals that use calcium carbonate to create their skeletons and shells.

There are many ways humans have damaged marine like; for example, pollution, over fishing, dredging, and blasting are just the obvious ways. Adding carbon dioxide to the atmosphere is a more hidden way of harming marine life; a way that slowly dissolves their bodies. Many sea creatures build the shell or exoskeleton using calcium carbonate. This is how it can be dissolved: CO2 + H2O H2CO3 HCO3- + H+ HCO3- H + + CO 3 2- CaCO 3 + 2H + + CO 3 2- Ca 2+ (i) + 2HCO 3 CaCO 3 + CO 2 + H 2 O Ca(HCO 3 ) 2

In this experiment, we will show that you also give off CO2 as you burn the food that youve eaten. We will detect the CO2 in two ways. Both ways show that the acidity of water will increase when CO2 is added. One way of showing it is by directly measuring pH. The other is the same as we did in the car exhaust lab, but this time, you will provide the CO2.

The amount of CO2 that dissolves in water depends on the temperature of water. You know this from experience. If you open a soda can while warm, its likely to spray all over as the CO2 leaves the water to become a gas. If cold, the CO2 stays dissolved in the water. We are going to blow into a beaker of ice water using a straw. The concentration of CO2 from our lungs is about 4% (thats about 4 CO2 molecules, 5 water (H2O) molecules, 15 oxygen (O2) molecules, and 76 nitrogen molecules (N2). With the car exhaust, CO2 concentration was about 12% (12 CO2, 75 nitrogen molecules, and 13 H2O.

CH3(CH2)6CH O2 8CO2 + 9H2O 12.5 to x = 20 to 80 ( 4 x 12.5)=50 50 molecules N2 : 8CO2 + 9H2O