Chapter 23.2, Problem 8R

To determine

To classify: The substances as a hydrocarbon or a substituted hydrocarbon.

Explanation of Solution

Introduction: Hydrocarbons contain carbon and hydrogen atoms. Replacing one or more hydrogen atoms by other elements in a hydrocarbon, a new compound is formed which is called substituted hydrocarbon.

Ethyne has the chemical formula ${\text{C}}_2{\text{H}}_2$ , thus containing two carbon atoms linked by triple covalent bond and two hydrogen atoms linked to the carbon atoms by single bond. So, ethyne is a hydrocarbon.

Tetrachloroethene has the chemical formula ${\text{Cl}}_2{\text{C=CCl}}_2$ . Chlorine atoms replace the four hydrogen atoms of ethene. So, tetrachloroethene is substituted hydrocarbon.

Ethanol has the chemical formula ${\text{C}}_2{\text{H}}_5\text{OH}$ . The −OH group replaces a hydrogen atom of ethane to form ethanol. Thus, ethanol is a substituted hydrocarbon.

Benzene has the chemical formula ${\text{C}}_6{\text{H}}_6$ , thus containing only carbon and hydrogen atoms.so, benzene is a hydrocarbon.

Propane has the chemical formula ${\text{C}}_3{\text{H}}_8$ , containing only carbon and hydrogen atoms.so, propane is a hydrocarbon.

Acetic acid has the chemical formula ${\text{CH}}_3\text{COOH}$ . The −COOH group replaces a hydrogen atom of methane to form acetic acid. Thus, acetic acid is a substituted hydrocarbon.

Conclusion: Ethyne, benzene and propane are hydrocarbons, whereas, tetrachloroethene, ethanol and acetic acid are substituted hydrocarbons.