1. <em>Identifying alkanes
</em>
Answer:
d. C₁₄H₃₀
Explanation:
The general formula of an alkane is , where n is the number of C atoms.
If n = 14, 2n+2 =30. This compound is an alkane
a. is <em>wrong</em>. 2n+2 = 6. There is a deficiency of four H atoms.
b. is <em>wrong</em>. 2n+2 = 12. There is a deficiency of two H atoms.
c. is <em>wrong</em>. 2n+2 = 16. There is a deficiency of four H atoms.
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2. <em>Identifying isomers
</em>
Answer:
a. C₃H₈
Explanation:
A 3-carbon alkane is too short to have isomers. The smallest alkane that can have isomers has <em>four carbon atoms</em>.
Thus <em>a</em>. (9 isomers), <em>b</em>. (3 isomers) and <em>d.</em> (many isomers!) are all <em>wrong</em>.
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3. <em>Naming alkanes
</em>
Answer:
a. 2,2-Dimethylbutane.
Explanation:
1. Identify and name the longest continuous chain of carbon atoms (the main chain has 4 C; ∴ base name = <em>butane</em>).
2. Identify and name all the substituents [two 1C substituents (<em>methyl</em>)].
3. Number the main chain from the end closest to a substituent.
4. Identify the substituents by the number of the C atom on the main chain. Use hyphens between letters and numbers (<em>2-methy</em>l).
5. When there is more than one substituent of the same type, identify each substituent by its locating number and use a multiplying prefix to show the number of each substituent. Use commas between numbers (<em>2,2-dimethyl</em>).
6. Put the names of the substituents in front of the base name with no spaces. The name is 2,2-dimethylbutane.