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CHE 105/110 Introduction to Chemistry - Exercises and Answers

Hydrocarbons

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QUESTION ANSWER

1.

Define hydrocarbon. What are the two general types of hydrocarbons?

1.

an organic compound composed of only carbon and hydrogen; aliphatic hydrocarbons and aromatic hydrocarbons

3.

Indicate whether each molecule is an aliphatic or an aromatic hydrocarbon; if aliphatic, identify the molecule as an alkane, an alkene, or an alkyne.

  1.  

    Structural formula of butane showing single covalent bonds (short lines) between Hydrogen and Carbon atoms, and between atoms of Carbon atoms.

  2.  

    Structural formula of butane showing single covalent bonds (short lines) between Hydrogen and Carbon atoms and between carbon atoms.

  3.  

    Structural formula of 2-butene showing single covalent bonds (short lines) between Hydrogen and Carbon atoms and between Carbon atoms. The double covalent bond between two Carbon atoms is indicated by the double short line. The position of this double bond is indicated in the compound name.

3.

  1. aliphatic; alkane
  2. aromatic
  3. aliphatic; alkene

5.

Indicate whether each molecule is an aliphatic or an aromatic hydrocarbon; if aliphatic, identify the molecule as an alkane, an alkene, or an alkyne.

  1.  

    Structural formula of cyclo-propane showing single covalent bonds (short lines) between Hydrogen and Carbon atoms and between Carbon atoms.

  2.  

    Structural formula of cyclo-propene showing single covalent bonds (short lines) between Hydrogen and Carbon atoms and between Carbon atoms. The double covalent bond between two Carbon atoms is indicated by the double short line.

  3.  

    Aromatic compound showing the benzene unit (six Carbon atoms in a ring, with alternating single and double Carbon bonds) and three methyl substituents (-CH3)in the structure.

5.

  1. aliphatic; alkane
  2. aliphatic; alkene
  3. aromatic

7.

Name and draw the structural formulas for the four smallest alkanes.

7.

 

 
Structural formulas of the four simplest members of the Alkanes hydrocarbon family.

9.

What does the term aromatic imply about an organic molecule?

9.

Aromatic means that the molecule has a benzene ring.

11.

Explain why the name 1-propene is incorrect. What is the proper name for this molecule?

11.

The 1 is not necessary. The name of the compound is simply propene.

13.

Name and draw the structural formula of each isomer of pentene.

 

13.

 

 
Two members of the alkenes family. The position of the double bond between Carbon atoms is indicated in the compound name.

15.

Write a chemical equation for the reaction between methane and bromine.

15.

CH4 + Br2 → CH3Br + HBr

17.

Draw the structure of the product of the reaction of bromine with propene.

17.

The compound 1,2 dibromopropane has two atoms of Bromine substituting the Hydrogen on indicated positions.

19.

Draw the structure of the product of the reaction of hydrogen with 1-butene.

19.

 
The structural formula of butane.

21.

Write the balanced chemical equation for the combustion of heptane.

21.

C7H16 + 11O2 → 7CO2 + 8H2O

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