1. The Carbon Cycle
HS-LS2-5

2. Making Calcium Carbonate
This process involves:
Geosphere (calcium)
Atmosphere (CO2)
Hydrosphere (H2O)

3. Water that contains dissolved CO2
Atmosphere
CO2
Geosphere Ca
Hydrosphere
H2O
As precipitation moves through the air, it picks up CO2 and makes Carbonic Acid (H2CO3)
Carbonic Acid (H2CO3) is a weak acid. It dissolves limestone in the soil making Calcium Carbonate (CaCO3)
Water that contains dissolved CO2
Calcium Carbonate (CaCO3) makes its way to the ocean for life to use it.

4. Think of examples of where Carbon can be found on Earth.
Write as many examples as you can on your group’s white board.

5. What are some sources of Carbon on Earth?
Lithosphere
The rigid outer part of the earth, consisting of the crust and upper mantle.
Calcium carbonate (CaCO3) in rocks and minerals
Hydrosphere
Water that contains dissolved CO2.
Biosphere
Sugars or carbohydrates (CnH2nOn) in living organisms.
Atmosphere
Carbon dioxide (CO2)

6. How does Carbon Cycle through the spheres?
As a group, create a diagram on your white board to show how carbon cycles through the lithosphere, hydrosphere, atmosphere and biosphere.

8. Volcanos, Hot Springs, Mid-Ocean Vents put out CO2

9. Fossil Fuels
When dead plants and animals slowly decay under high pressure and high temperatures, they may eventually form pools of energy known as fossil fuels.
Coal, oil, and natural gas are fossil fuels.
People burn fossil fuels to release the energy stored in them. The energy is used for heat, operating automobiles, etc.

10. Green Plants
Green plants play a very important role in the carbon cycle.
They absorb carbon dioxide (CO2) from the atmosphere and produce carbon- containing sugars.
This process is called photosynthesis.

11. 6 CO2 + 6 H2O + sunlight ------> C6H12O6 + 6 O2
Photosynthesis
The process of photosynthesis requires water (H2O). It also produces water as well as oxygen (O2).
The net chemical reaction for the process of photosynthesis is:
6 CO2 + 6 H2O + sunlight > C6H12O6 + 6 O2

12. Animals
Animals eat plants to obtain the energy trapped during photosynthesis.
As the animals' bodies break down the carbohydrates in the plant tissue, CO2 is released to the atmosphere.
This process is called cellular respiration.

13. 6 O2 + C6H12O6 ------> 6 H2O + 6 CO2
Cellular Respiration
The net chemical reaction for the process of respiration is the exact opposite of photosynthesis:
6 O2 + C6H12O6 ------> 6 H2O + 6 CO2
Plants respire also as they break down the organic molecules in themselves in order to release the stored energy.
Plants and animals also release CO2 to the atmosphere when they decay.