Chemistry

1
Chemistry
Chemical Reactions
2
Biosphere II
Engagement
3
Engagement
Biosphere II habitat biome
4
Engagement
Biosphere II agriculture biome
5
Engagement
Biosphere II rainforest biome
6
Engagement
Biosphere II Desert and Savannah biomes
7
Engagement
Biosphere II coral reef biome
8
Engagement
Biosphere II lungs
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Engagement
Biosphere II the idea

• Humans can design and build a totally contained
  ecosystem
• SOMEDAY, an ecosystem could sustain life on Mars
  without outside help
• September 1991

10
Engagement
Biosphere II the problem

• Falling OXYGEN levels
• Initial levels ? 21 v
• Falling by 0.5 per month
• Carbon dioxide levels rising
• Fluctuated 2000ppm to 4000ppm
• High but not dangerous
• Stabilized ? 4000ppm

11
Engagement
Biosphere II the problem

• Crew would ADJUST
• January 1993 ?16 months
• OXYGEN Level at 14 ? 4,360 meters (about
  14,300 feet)
• Added oxygen
• Crew recovered and finished the final 8 months

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Engagement
Biosphere II where is the oxygen?

• Design a poster to give possible explanations for
  the decreasing oxygen levels.
• What solutions might be possible if Biosphere II
  had been located on Mars?

13
Engagement
Biosphere II what happened

• Weather?
• Clouds, slow plant growth
• Manufactured soils?
• Rust
• Nitrogen in the soil ? nitrates
• Water Supply ? Not there
• Microbial metabolization?
• Microbes using oxygen to process excess organic
  matter in soil
• Carbon dioxide should have been 40,000ppm

14
Engagement
Biosphere II what happened

• Calcium silicate ? calcium carbonate
• No Limestone
• No Scale on pipes
• Rubber membranes
• No leakage
• Concrete?
• Lots of concrete in the facility
• Calcium carbonate 10 times more

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Engagement
Biosphere II what happened

• Concrete
• Sand
• Gravel
• Binding agent- portland cement
• Portland Cement
• Powered mixture of limestone
• Clay
• Sand
• 1350 Co in a rotating kiln
• Calcium silicates and calcium aluminates
• Mixed with water
• Calcium silicate and calcium hydroxide

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Engagement
Biosphere II what happened

• Calcium silicate hydrates
• Strength
• Calcium hydroxide
• Secret to the missing carbon dioxide
• Diffusion
• Carbon dioxide diffuses into the cement
• Reacts with calcium hydroxide
• Forms calcium carbonate and water
• Ca(OH)2 CO2 ? CaCO3 H2O

17
Engagement
Biosphere II what happened

• Normal Conditions ? slow reaction
• Carbon dioxide ? 10 X higher
• In 2 years ? 2cm penetration
• 500,000 to 1,500,000 moles of carbon dioxide were
  HIDING in the concrete

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Engagement
Biosphere II what happened

• Structural ? calcification of concrete
• Buried Iron reinforcing bars
• pH 8 ? bars will not corrode
• pH will decrease causing corrosion

CO2 H2O ? H2CO3
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Engagement
Biosphere II what happened

• Problems and solutions
• What problems could be caused by this unexpected
  situation?
• What would have happened if the structure had
  been located on Mars?
• How would you meet this challenge?

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Engagement
Biosphere II what happened

• Solutions
• Concrete
• Seal all surfaces
• Soils
• Too much organic matter
• New formulations
• Clouds?
• New lights

CO2 H2O ?  H2CO3
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Engagement
Biosphere II the future

• Columbia University ? ecology experiments
• Study solutions to original experiment
• Carbon dioxide levels
• Slowed coral growth
• Drought conditions in the rainforest

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Exploration
Biosphere II Out of Oxygen HO 5.1
In this activity you will determine if various
substances contain calcium carbonate by reacting
each with vinegar.

• Materials
• Safety goggles
• 500 mL vinegar
• 6 small plastic cups

• Samples (small pieces)
• Eggshells
• Potato peels
• Chalk
• Glass
• Limestone
• Granite

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Exploration
Biosphere II procedure HO 5.1

• Put on your safety goggles.
• Collect samples to be tested and describe them.
• Predict which samples contain calcium carbonate.
• Place each substance to be tested in a labeled
  plastic cup.
• Pour in enough vinegar to cover each sample.
• Carefully observe each sample during the class
  time and make three observations.
• Record your observations.

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Explanation
Biosphere II

• How did you detect the presence of calcium
  carbonate? Why?
• What samples contain calcium carbonate? 
• What type of property is being tested in the
  investigation?
• What is a chemical property? How does it differ
  from a physical property?

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Elaboration
Alka-Seltzer HO 5.2

• Many people take Alka-Seltzer to soothe an acid
  stomach. The tablet contains sodium hydrogen
  carbonate and citric acid. When Alka-Seltzer is
  added to water, the acid and base react
  chemically to neutralize each other according to
  the following balanced chemical equation

NaHCO3 HC6H7O7 ? CO2 H2O NaC6H7O7 Energy

• Record the active and inactive ingredients of
  the Alka-Seltzer.
• Predict what happens when your tablet is dropped
  into water.
• Describe the change that occurs.

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Elaboration
Alka-Seltzer HO 5.2

• Materials
• Two 250 mL beakers
• Thermometer
• Two Alka-Seltzer tablets
• Masking tape
• Two stop watches
• 1 Liter bottle
• Balloon
• Balance

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Alka-Seltzer HO 5.2
Elaboration

• Which tablet will dissolve first? Why?
• Write a hypothesis.
• Design an experiment to test your hypothesis.
• Graph your results.
• Compare your results with the rest of the class.
  How did your procedures differ? How did it
  affect your results?
• As a group discuss the changes that took place.
• Using the data, design an experiment to measure
  the density of the gas. Carefully describe the
  procedure in writing.

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Elaboration
Alka-Seltzer procedure HO 5.2
Dissolve two Alka-Seltzer tablets in water at two
different temperatures.

• Which tablet will dissolve first? Why?
• Write a hypothesis.
• Design an experiment to test your hypothesis.

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Elaboration
Alka-Seltzer results HO 5.2

• Compare your results with the rest of the class.
  How did your procedures differ? How did it
  affect your results?
• As a group discuss the changes that took place.
• Using the data, design an experiment to measure
  density of the gas.
• Carefully describe the procedure.

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Ion Cards HO 5.3
Exploration

• Matter can be neither created nor destroyed.
• Use your ion cards to find the products and
  balance the equations on Handout 5.3.

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Chemical Reactions HO 5.4
Evaluation

• What happened to the oxygen in Biosphere II?
• What is a physical property?
• Give an example.
• What is a chemical property?
• Give an example.