3SAS (p.235) #31-38 and 3SBS (p.258) #1-10

7/23/13

3SAS (p.235) #31-38
31. a. name: Propane; molecular formula: C3H8
      b. name: Pentane; molecular formula: C5H12

32. The suffix -ane in the carbon-carbon bonding in hexane implies that hexane is an alkane.

33. Yes, each of the three molecules are isomers of one another because they all have identical molecular formulas, but just a different arrangement of atoms.

34.

35. Butane is the shortest-chain alkane that demonstrates isomerism because it is and alkane with four or more carbon atoms that can be demonstrated as straight-chain structures, branched-chain structures, or ring structures.

36. Both representations are correct because it doesn't change the molecular formula, they are just demonstrated in different ways; therefore they are structural isomers.

37. a. Two hexane structural isomers, one straight chained, and the other branched-chained:

      b. Of the two isomers, the straight-chain would have the lowest boiling point because it has a weaker intermolecular force. Where as the branch-chain molecule has a greater intermolecular force, resulting in a higher boiling point.

38. a. A short-straight chain would have the lowest boiling point because of the weaker intermolecular forces. And because of this the bonds are much easier to break apart.
     b. A short-branched chain would have the lowest boiling point because longer branched-chains have a stronger molecular force.
     c. A long, straight chain has a lower boiling point because it has a weaker intermolecular force than a short, branched-chain.

3SBS (p.258) #1-10
1. Petroleum is sometimes considered "buried sunshine" because as a fossil fuel, it originates from biomolecules of prehistoric plants and animals, and as sunlight is captured by these prehistoric gren plants during photosynthesis, the energy released is the burning of petroleum.

2.  a. Potential energy is energy of position, or stored energy ready to be released. An example is the energy within an unreleased winded up spring toy.
     b. Kinetic energy is energy related to motion. An example is a car rolling down a hill.

3. During a chemical reaction is an energy-releasing reaction that takes place, the bonds break and reactant atoms reorganize to form new bonds and release energy. If more energy is released than originally started with, the reaction is exothermic, but if less energy is released than originally started with, the reaction is endothermic.

4. A molecule of butane has more potential energy because it has more carbon atoms and a higher boiling point than methane. Additionally, the bonds of butane are harder to break apart, resulting in a higher potential energy.

5. a. Potential energy
    b. Potential energy
    c. Kinetic energy
    d. Potential energy
    e. Kinetic energy

6. Energy is required to break chemical bonds because energy causes reactant bonds to break and eventually reorganize to form new product bonds and energy.

7. a. Burning wood in a campfire: exothermic because more energy (heat) is released than is required to begin the chemical reaction.
    b. Cracking large hydrocarbon molecules: endothermic because the molecule is being broken up; therefore, energy is being used.
    c. Digesting a candy bar: endothermic because the molecule is being broken up; therefore energy is being used.

8. Burning a candle is an exothermic reaction because the energy released in the product is greater than the energy used in the reactant to break the bond. Basically more energy is given off than is added, making it exothermic.

9.

10. The law of conservation of energy states that energy is neither created nor destroyed in any mechanical, physical, or chemical process.