Exercises

Part I

  1. Explain why the symbol for an atom of the element oxygen and the formula for a molecule of oxygen differ.
  2. Explain why the symbol for the element sulfur and the formula for a molecule of sulfur differ.
  3. Write the molecular and empirical formulas of the following compounds:
    1. Figure A shows a carbon atom that forms two, separate double bonds with two oxygen atoms.
    2. Figure B shows a hydrogen atom which forms a single bond with a carbon atom. The carbon atom forms a triple bond with another carbon atom. The second carbon atom forms a single bond with a hydrogen atom.
    3. Figure C shows a carbon atom forming a double bond with another carbon atom. Each carbon atom forms a single bond with two hydrogen atoms.
    4. Figure D shows a sulfur atom forming single bonds with four oxygen atoms. Two of the oxygen atoms form a single bond with a hydrogen atom.
  4. Write the molecular and empirical formulas of the following compounds:
    1. Figure A shows a structural diagram of four carbon atoms bonded together into a chain. The two carbon atoms on the left form a double bond with each other. All of the remaining carbon atoms form single bonds with each other. The leftmost carbon also forms single bonds with two hydrogen. The second carbon in the chain forms a single bond with a hydrogen atom. The third carbon in the chain forms a single bond with two hydrogen atoms each. The rightmost carbon forms a single bond with three hydrogen atoms each.
    2. Figure B shows a structural diagram of a molecule that has a chain of four carbon atoms. The leftmost carbon atom forms a single bond with three hydrogen atoms each and single bond with the second carbon atom. The second carbon atom forms a triple bond with the third carbon atom. The third carbon atom forms a single bond to the fourth carbon atom. The fourth carbon atom forms a single bond to three hydrogen atoms each.
    3. Figure C shows a structural diagram of two silicon atoms are bonded together with a single bond. Each of the silicon atoms form single bonds to two chlorine atoms each and one hydrogen atom.
    4. Figure D shows a structural diagram of a phosphorus atom that forms a single bond to four oxygen atoms each. Three of the oxygen atoms each have a single bond to a hydrogen atom.
  5. Determine the empirical formulas for the following compounds:
    1. caffeine, C8H10N4O2  
    2. fructose, C12H22O11  
    3. hydrogen peroxide, H2O2  
    4. glucose, C6H12O6  
    5. ascorbic acid (vitamin C), C6H8O6
  6. Determine the empirical formulas for the following compounds:
    1. acetic acid, C2H4O2  
    2. citric acid, C6H8O7   
    3. hydrazine, N2H4   
    4. nicotine, C10H14N2   
    5. butane, C4H10
  7. Write the empirical formulas for the following compounds:
    1. Figure A shows a structural diagram of two carbon atoms that form a single bond with each other. The left carbon atom forms single bonds with hydrogen atoms each. The right carbon forms a double bond to an oxygen atom. The right carbon also forms a single bonded to another oxygen atom. This oxygen atom also forms a single bond to a hydrogen atom.
    2. Figure B shows a structural diagram containing a leftmost carbon that forms single bonds to three hydrogen atoms each. This leftmost carbon also forms a single bond to a second carbon atom. The second carbon atom forms a double bond with an oxygen atom. The second carbon also forms a single bond to a second oxygen atom. This oxygen atom forms a single bond to a third carbon atom. This third carbon atom forms single bonds with two hydrogen atoms each as well as a single bond with another carbon atom. The rightmost carbon atom forms a single bond with three hydrogen atoms each.

Part II

  1. Open the Build a Molecule simulation and select the “Playground” tab. Select an appropriate atoms “Kit” to build a molecule with two carbon and six hydrogen atoms. Drag atoms into the space above the “Kit” to make a molecule. A name will appear when you have made an actual molecule that exists (even if it is not the one you want). You can use the scissors tool to separate atoms if you would like to change the connections.
    1. Draw the structural formula of this molecule and state its name.
    2. Can you arrange these atoms in any way to make a different compound?
  2. Use the Build a Molecule simulation to repeat question 1, but build a molecule with two carbons, six hydrogens, and one oxygen.
    1. Draw the structural formula of this molecule and state its name.
    2. Can you arrange these atoms to make a different molecule? If so, draw its structural formula and state its name.
    3. How are the molecules drawn in (a) and (b) the same? How do they differ? What are they called (the type of relationship between these molecules, not their names).
  3. Use the Build a Molecule simulation to repeat question 1, but build a molecule with three carbons, seven hydrogens, and one chlorine.
    1. Draw the structural formula of this molecule and state its name.
    2. Can you arrange these atoms to make a different molecule? If so, draw its structural formula and state its name.
    3. How are the molecules drawn in (a) and (b) the same? How do they differ? What are they called (the type of relationship between these molecules, not their names)?

Part III

  1. What property of carbon makes it essential for organic life?
  2. Compare and contrast saturated and unsaturated triglycerides:

Part IV

  1. Why are biological macromolecules considered organic?
  2. What role do electrons play in dehydration synthesis and hydrolysis?
  3. Name the reaction in which macromolecules are produced:
  4. Name the reaction in which macromolecules are broken down: