Convert the condensed formula HCCCH(CH3) into its expanded structure. Be sure to draw all hydrogen atoms.
The Correct Answer and Explanation is:
Expanded Structure of HCCCH(CH₃):
The condensed formula HCCCH(CH₃) can be expanded into its full structure as follows:
Expanded (complete) structure with all atoms and bonds shown:
mathematicaCopyEdit H H H
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H–C≡C–C–C–H
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H H
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CH₃
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H H H
Explanation
The condensed formula HCCCH(CH₃) represents a hydrocarbon molecule, and the goal is to write out the full structural formula including all carbon (C) and hydrogen (H) atoms, and showing the types of bonds (single, double, triple) between the atoms.
Let’s break the molecule down:
- H–C≡C–: This is the beginning of the molecule. “H” is a hydrogen bonded to a carbon atom. The carbon (C) is triple-bonded (≡) to another carbon atom. This part represents a terminal alkyne group. So:
- The first carbon is bonded to one H and has a triple bond to the next carbon.
- The second carbon in the triple bond has only one remaining bond available.
- –C–CH₃: After the triple bond, the next carbon is bonded to a methyl group (CH₃) and another hydrogen atom to satisfy its valency of 4.
So now we can label each carbon:
- C1: First carbon, bonded to 1 hydrogen and triple bonded to C2.
- C2: Second carbon, triple bonded to C1 and single bonded to C3.
- C3: Single bonded to C2, single bonded to C4 (which is the CH₃ carbon), and has one hydrogen.
- C4 (CH₃): A methyl group (–CH₃), bonded to C3 and 3 hydrogens.
Adding all the hydrogen atoms to satisfy carbon’s tetravalency, we have:
- C1: 1 H
- C2: 0 H (all 4 bonds used in triple and single bonding)
- C3: 1 H
- C4: 3 H (methyl group)
Thus, the complete structure is but-2-yne, substituted with a methyl group on the 3rd carbon, more systematically named 3-methyl-1-butyne.Tools
