Author Question: Explain the flammability of aromatic versus aliphatic molecules from an energy perspective assuming ... (Read 86 times)

neverstopbelieb · **on:** Aug 19, 2018

Explain the flammability of aromatic versus aliphatic molecules from an energy perspective assuming the bond strength of a C==C bond is approximately twice as much as the bond strength of a CC bond. Also, that the bond strength of a hydrogen attached to a benzene is about 20 higher than the bond strength of hydrogen attached to propylene.

What will be an ideal response?

Question 2

Explain in thermodynamic and molecular structure terms why small molecules are more readily solvated than large molecules.

What will be an ideal response?

Question 3

Describe the Izod toughness test.

What will be an ideal response?

kusterl · **Reply #1 on:** Aug 19, 2018

Answer to Question 1

Flammability is a measure of a material's ability to perpetuate a flame. This is done as heat is released when bonds are formed. Typically the bonds that reform are those between hydrogens and oxygens. As the energy in bonds increases, it becomes more difficult to break the bonds (requires higher temperatures) and change it to heat energy. Therefore, the carbon double bonds in the benzene ring of the aromatics will increase the energy required for burn as well as the bond between the hydrogens and the benzene. In order to burn the aromatics, the applied heat to break bonds and begin

Answer to Question 2

In thermodynamic terms, solvation will occur when the free energy for the solvation is negative, that is, the energy is more favorable for solvation than for staying in the solid state. Either the enthalpy term ( H), the entropy term (T S), or both, must be negative and dominate whichever of the terms might be positive. The enthalpy term will only be negative when the solvation bonds are stronger than the polymer bonds. This rarely happens. Hence, the entropy term must be more negative than the enthalpy term is positive. This can happen at high temperatures because T becomes very large. It can also happen when the entropy,
S, is large. The entropy will be large when great randomness is associated with the system. Because small polymer molecules can become more random when solvated than can large molecules, small molecules are more favorable to a dominating entropy term and will therefore solvate more easily.

Answer to Question 3

The sample