NAME: ANSWER KEY
ChemV21L: Quiz #6
I. Physical Properties: Test Tube #1 contains a sample of nonane and Test Tube #2 contains a
sample of 2-pentene. Answer the following questions that compare these two hydrocarbons.
1.) Would nonane, 2-pentene, both, or neither be soluble in water (polar solvent)? Explain.
NEITHER. Recall that all hydrocarbons are nonpolar, meaning that they will not
dissolve in polar solvents (like dissolves like).
2.) Would nonane, 2-pentene, both, or neither, be soluble in benzene (nonpolar solvent)?
Explain.
BOTH. Recall that since all hydrocarbons are nonpolar, they will dissolve in nonpolar
solvents (like dissolves like).
3.) Which would you expect to evaporate faster: nonane or 2-pentene? Why?
2-pentene. 2-pentene (C5H10) has a much lower molecular weight than nonane
(C9H20). Since volatility increases with decreasing molecular weight, the smaller
molecule will evaporate more easily and quickly.
4.) Which, if any, would react with potassium permanganate (KMnO4) to oxidize?
2-pentene. Recall that saturated hydrocarbons (alkanes, e.g., nonane) do not oxidize;
the double bond in the alkene of 2-pentene will oxidize into a diol when exposed to
potassium permanganate.
5.) Which, if any, would react with bromine (Br2) only under UV light?
nonane. Recall that the double bond in alkenes (e.g., 2-pentene) will be brominated
immediately (halogenation reaction). For hydrocarbons, exposure to UV light will cause
the reaction to progress forward.
6.) Consider 2-pentene. Draw the structure of the compound that would result from
bromination with Br2 (reaction 5 above) AND name it appropriately.
2,3-dibromopentane. The bromine adds across the double bond and reduces it to a
single (haloalkane product).
Br
Br