Living in a Carbon World
Part C: Building Carbon Compounds
Scientists predict that more than ten million different carbon compounds are in existence on Earth today. In this section, you will carry out four short investigations to explore how carbon atoms can join with other types of atoms to form the millions of different types of carbon compounds that can be found in the Geosphere and Biosphere. To get you started thinking about carbon's ability to form so many different types of carbon compounds, watch this short NPR video clip, It's All About Carbon: Episode 1.
NOTE: If the video does not load, you can watch the video here: Episode 1: Global Warming, It's All About Carbon - YouTube You can also follow this link where you can watch other episodes of this NPR series.
Laboratory Investigation 1: Evidence for a Chemical Change
In the video you just watched, you learned that carbon atoms bond easily and strongly with other atoms to form many different types of carbon compounds. In this investigation, you will look for evidence of a new carbon compound being formed when two carbon compounds are brought together: the CO2 from your own breath and a solution of calcium hydroxide Ca(OH)2.
- (Class demo) Chalk is made of calcium carbonate (CaCO3). When vinegar is added to chalk, fizzing occurs indicating that chalk is made of calcium carbonate. You will use the vinegar test to indicate the presence of calcium carbonate.
- Examine the limewater and describe its appearance. Limewater is the common name for saturated calcium hydroxide solution, Ca(OH)2 (aq).
- Place one of the drinking straws into the lime water and blow gently into the liquid. DO NOT INHALE OR BLOW TOO HARD. Continue exhaling through the straw until a white precipitate (solid) forms. The solution should look very milky with small particles.
- Place the coffee filter over the empty cup. Carefully pour the lime water into the cup through the filter to separate the precipitate from the liquid.
- Put the filter with white precipitate aside and allow it to dry and solidify.
- Place a drinking straw into a cup of regular water (instead of limewater) and blow gently. Observe what happens. This serves as your experimental control.
- To prove that the substance you filtered out of the lime water is indeed calcium carbonate, use the eyedropper to add a small amount of white vinegar to the precipitate.
Checking InDescribe how limewater and regular water react differently when carbon dioxide gas is added to each.
- What evidence did you observe that a new kind of carbon compound was formed in this investigation.
- Describe what happens to the carbon atoms in carbon dioxide (CO2) when you blow CO2 into the limewater?
- Why does this investigation serve as a model for understanding chemical change as a key component of the carbon cycle.
Laboratory Investigation 2: Modeling Photosynthesis and Cell Respiration
In this investigation, you will use a "ball and stick" molecular model kit to investigate how the two key biosphere processes of photosynthesis and cell respiration create new carbon compounds. Gather your materials and follow the instructions for modeling photosynthesis and cell respiration below:
6CO2 + 6H2O ==> C6H12O6 + 6O2
2. Build your glucose molecule using the image of a glucose molecule pictured on the right to guide you. If you click to enlarge the image, you will easily see how the carbon, hydrogen and oxygen atoms are bonded to each other. NOTE: Do not take apart the glucose molecule until you start Investigation 3:
3. Use the remaining oxygen atoms and bonds to build six O2 molecules (O=O). These oxygen gas molecules are released to the air and provide some of the necessary oxygen for life on earth.
4. Examine the equation for cell respiration pictured on the right. The chemical equation for cell respiration is:
C6H12O6 + 6O2==> 6CO2 + 6H2O + energy for cell functions
Then, answer the Checking In questions below:
Laboratory Investigation 3: Biosynthesizing New Biomolecules From Glucose
- Take your glucose molecule and join with at least one other team.
- Take apart the glucose molecules. NOTE: You do not have to disconnect all of the bonds from the atoms.
- Use the atoms and bonds from both teams to build a new biomolecules organic carbon compounds produced in living things; examples include carbohydrates, lipids(fat, soils, waxes), and DNA. . Your biomolecule can take any shape you like. The one rule you must follow is that no "electron bond prong" is left unconnected to another atom. It is possible to have a few atoms and bonds leftover when you build your biomolecule. NOTE: Your teacher may decide to produce you with nitrogen atoms. Using these atoms will allow you to build protein molecules.
- When you are finished building your new biomolecules, compare them with other biomolecules made by other teams.
Look at the the other biomolecules the class has made from the original glucose biomolecules.
- How are they similar? How are they different?
- If you had a thousand glucose biomolecules, how many different types of biomolecules do you think you could make? Why?
- Imagine that carbon could only form one electron bond as opposed to four. What effect might this have on the size and diversity of molecules you have been able to build so far?
Laboratory Investigation 4: Biosynthesis of Large Complex Biomolecules using CHNOPS acronym for carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur atoms; 97% of organisms are made of just these six elements
The cells and tissues in this squirrel and tree are comprised mostly of large, complex carbon compounds such as DNA and proteins. Photo courtesy of H. Zefram, Germany. Wikicommmons.
The biomass of all organisms is comprised mostly of proteins, carbohydrates, nucleic acids (DNA, RNA), and lipids (fats oils and waxes). Glucose and other carbohydrates contain carbon, hydrogen and oxygen atoms. However, organisms in the biosphere build millions of different biomolecules that contain nitrogen, phosphorus and sulfur. As a matter of fact, 97% of a living organism is made of only six elements; carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur or CHNOPS for short. Other elements such as magnesium and iron are also important but in very small quantities. Lack of any of these soil nutrientsnutrients in soil that are essential for plant growth; the most important soil nutrients include nitrogen, phosphorus, magnesium and sulfur. will limit plant growth and carbon storage. In this investigation, you will examine several Jmol images of biomolecules and identify the types of elements(atoms) in each.
- Make a three column chart in your Lab notebook or on a separate piece of paper. Give your chart the following headings:
- Column A = Name of biomolecule (ex. DNA, fructose etc.);
- Column B = Type of biomolecule (ex. carbohydrate, protein etc.);
- Column C = Types of atoms (elements). Use first letters (C H N O P S Mg I);
Stop and Think:1: Explain why the carbon atoms in carbon compounds such as proteins and DNA originally came from CO2 molecules in the atmosphere.
2: Explain why a lack of soil nutrients (ex. nitrogen, phosphorus, sulfur and magnesium) limits a tree's ability to grow and store carbon.
3: Explain how trees and all other organisms in the biosphere are able to make millions of different configurations of carbon compounds.
Want to learn more about carbon compounds, biomolecules, CHNOPS, soil nutrients and more? Check out these resources.
- Research the latest research! New research on the carbon cycle, climate and the environment is on-going. You can use ScienceDaily and Phys.org to research recent research on the relationship between the carbon cycle and other biochemical cycles by using combinations of the following tags: carbon cycle, carbon storage/sequestration, CO2 fertilization, trees, forests, soil nutrients. Here is an example: Soil nutrients limit ability of plants to slow climate change
- Use MolView to explore Jmol biomolecules made by many different types of organisms.
- Watch Biogeochemical Cycles and CHNOPS from Paul Anderson's BozemanScience for an in-depth molecular understanding of biogeochemical cycles and CHNOPS.
- Watch the other videos in the Its All About Carbon series from NPR.