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Why do low molecular weight alkanes have such low boiling points?
Only weak intermolecular van der Waal forces attract the molecules to each other; these forces are easily broken at low temperatures
How many isomers of C6H14 are possible?
- 5 total
What prefixes are used to describe alkane derivatives with alkyl chains of 8, 9, and 12 carbons?
8 = oct; 9 = non; 12 = dodec
Why is the name 5-methylhexane incorrect?
(methyl) group would be at C-2 following the IUPAC rules, i.e. 2-methylhexane
How many isomeric butyl substituents are possible?
-butyl; isobutyl; t
Give an alternate name for t-butylcycloheptane using the IUPAC form for the substituent
Why do branched alkanes typically have lower boiling points than their unbranched isomers?
The branched substituents get in the way of the alkyl chains interacting and being attracted; less intermolecular interaction leads to a lower boiling point
Why do alkanes not dissolve in water?
They are incompatible and do not attract; water is very polar, alkanes are very non-polar
What oxidation numbers would you assign to the C atoms in CH3CH3, H2C=O, CH3Cl, and O=C=O?
- -3 in CH3CH3
- 0 in H2C=O
- -2 in CH3Cl
- +4 in CO2
What type of valence orbitals are used by C in H2C=CH2 to form bonds?
C will use sp2 orbitals for sigma bonds and a p orbital for the pi bond
What are the expected bond angles around each C atom in CH3CH=CH2?
109.5o around the C atom in CH3; 120o around the two C atoms in the double bond
Provide the IUPAC name for CH3CH2CH2CH(CH3)CH(CH3)CH2CH3
Give the generic formula for an alkane
Which would have the higher boiling point, heptane or 2-methylhexane?
Heptane; linear alkane with no branching interrupting intermolecular attractions
Give an alternate name for the isopropyl substituent
What is wrong with the name 2-methyl-3-ethylnonane?
The ethyl should go before the methyl to keep the substituents correctly alphabetized
Give the generic molecular formula for a cycloalkane
What products are formed when any alkane is combusted?
CO2 and H2O
Which molecule contains the most highly oxidized C atom, CH4, CH3OH, or CO2?
Which molecules contain the most unsaturation, alkenes, alkynes, or alkanes?
Alkynes (2 pi bonds)