HW #13

3SAS #31-38

31. (a) Propane; molecular formula: C3H8
      (b) Pentane; molecular formula: C5H12

32. The suffix -ane implies that hexane is an alkane.

33. Yes because they all have the same molecular formulas, but just a different arrangement of atoms.

34.

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

36. Both representations are correct because it doesn't change the molecular formula.They are structural isomers.

37. (a) 

      (b) The straight-chain has the lowest boiling point because it has a weaker intermolecular force.

38. (a) A short-straight chain has the lowest boiling point because of the weaker intermolecular forces. This makes the bonds easier to break apart.     (b) A short-branched chain has lowest boiling point because longer branched-chains have a stronger molecular forces.     (c) A long, straight chain has a higher boiling point because it has a stronger intermolecular forces.

3SBS  #1-10

1. Petroleum is sometimes considered "buried sunshine" it is a fossil fuel that originates from biomolecules of prehistoric plants and animals. The energy released by burning petroleum represents energy originally captured from sunlight by these prehistoric plants during photosynthesis.

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

3.  Chemical energy (form of potential energy), is stored in the bonds in chemical compounds. When an energy-releasing reaction takes place, the bonds break and reactant atoms form new bonds and release energy. If more energy is released than it originally started with, the reaction is exothermic. 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. The bonds of butane are harder to break apart, which results 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 because energy causes reactant bonds to break and reorganize to form new bonds and energy.

7. (a) Exothermic because more heat energy is released than is required to begin the chemical reaction.     (b) It's endothermic because the molecule is being broken up; therefore, energy is being used.
    (c) Endothermic because the molecule is being broken up; therefore energy is being used.

8. More energy is given off than is added, which makes it exothermic.

9.

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