41 8.2 Drawing and Interpreting Organic Formulas

Practice questions

1. Determine how many total hydrogens are in each of these line-bond formulas.
   1. 1. A structure with three carbons. The first and third carbons each have one hydroxyl group attached to it. The second carbon has a carbon-oxygen double bond.
      2. A structure with five carbons arranged in a straight chain. The first, fourth, and fifth carbons each have one hydroxyl attached. The first and the fifth carbons each have a carbon-oxygen double bond. The third carbon has a [latex]\ce{COOH}[/latex] group attached.
      3. How many hydrogens for arginine are shown here? A structure with six-carbon in a straight chain, except [latex]\ce{NH}[/latex] group located between first and second carbons. The first and fifth carbons have [latex]\ce{NH_{2}}[/latex] attached. The first carbon is also bonded to an [latex]\ce{NH}[/latex] group by a double bond between nitrogen and carbon. The sixth carbon has a hydroxyl group and a double-bonded oxygen attached.
      4. Two benzene rings fused.
2. How many carbon on this structure have no bonds to a hydrogen atom? The structure description: a benzene ring with a carboxylic group located at the first carbon. The second carbon has a [latex]\ce{OC=OCH_{3}}[/latex] attached.
   1. 1. 1
      2. 4
      3. None
      4. 3
3. How many hydrogens are bonded to carbon at each shown? The structure description: a hexane ring with a four-carbon chain attached to the first carbon of the hexane ring. The four carbon chain has a carbon-carbon double bond located between the third and fourth carbons, a hydroxyl attached to the fourth carbon and an ethyl group attached to the first carbon. The points shown are the four carbons in the four-carbon chain and two carbons in the attached ethyl group.

Answers

1. 1. 6
   2. 8
   3. 14
   4. 8
2. b
3. The first carbon on the four-carbon chain has one hydrogen. The second carbon on the four-carbon chain has two hydrogens. The third and the fourth carbons on the four-carbon chain have one hydrogen each. The first carbon in the ethyl group has two hydrogens, and the second carbon has three hydrogens.