Chapter 22, Problem 72A

Interpretation Introduction

Interpretation: The reason for benzene to be a less desirable fuel as compared to methane needs to be explained.

Concept Introduction: The heat of combustion is defined as the amount of heat released when a substance is burned in the presence of air.

Explanation of Solution

According to the question, the heat of combustion of methane is -890 kJ/mol. This is the amount of heat released after the combustion of 1 mol of methane. This heat or energy then can be used for various purposes. The heat released or energy after combustion of 1 mol of benzene is more as compared to methane. The value is -3268 kJ/mol. Here, due to the release of higher energy, benzene should be a good fuel source but it is not the case. Benzene alone is never used as a fuel because it is very harmful to the environment and human health.

Long-term exposure to benzene can cause blood disorders, liver damage, and cancer. Benzene is metabolized in the lungs and liver. The short-term exposure results in headaches, irritation in the eyes, dizziness as well as skin and respiratory problems. In the areas where benzene is in the atmosphere, water is not safe to drink. Air also has foul smells and soil is not considered healthy to yield crops. The photosynthesis process in plants can be affected by exposure to benzene.

Due to above-mentioned reasons, benzene is not used as fuel alone.