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Ch.7 - Thermochemistry
Chapter 7, Problem 112b

Hydrogen and methanol have both been proposed as alternatives to hydrocarbon fuels. Which fuel contains the most energy in the least mass?

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Step 1: Understand the problem. We need to compare the energy content per unit mass of hydrogen and methanol.
Step 2: Identify the energy content of each fuel. Hydrogen has an energy content of approximately 120 MJ/kg, while methanol has an energy content of about 22.7 MJ/kg.
Step 3: Compare the energy content per unit mass. Calculate the energy content per kilogram for both hydrogen and methanol.
Step 4: Analyze the results. Determine which fuel has a higher energy content per unit mass by comparing the values obtained in Step 3.
Step 5: Conclude which fuel contains the most energy in the least mass based on the comparison.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Energy Density

Energy density refers to the amount of energy stored in a given mass of fuel. It is typically expressed in units such as megajoules per kilogram (MJ/kg). Fuels with higher energy densities provide more energy for the same mass, making them more efficient for applications like transportation.
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Combustion Reaction

A combustion reaction is a chemical process in which a fuel reacts with oxygen to produce energy, carbon dioxide, and water. The efficiency and energy output of a fuel during combustion depend on its chemical structure and the completeness of the reaction, which can vary significantly between different fuels.
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Comparative Analysis of Fuels

Comparative analysis of fuels involves evaluating different fuels based on various criteria, including energy content, emissions, and cost. This analysis helps determine which fuel is more suitable for specific applications, such as transportation or heating, by comparing their performance metrics and environmental impact.
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