Chapter U5.103, Problem 1TAI

Interpretation Introduction

Interpretation: The method of comparison of different fuels is to be described.

Concept introduction: Combustion reactions are used to power vehicles, heat water and homes, and create electricity. But not all combustion reactions provide the same amount of energy.

Answer to Problem 1TAI

By increasing water temperature equate fuels by taking same amount of water and same amount of fuel.

Explanation of Solution

To compare different fuels measure the amount of energy that they transfer as a result of combustion. The most common method of measuring this energy is calorimetry. Energy transferred can be expressed in $\text{kcal}/\text{mol,}\text{kcal}/\text{g,}\text{kJ}/\text{mol,}\text{or}\text{kJ}/\text{g}$ . During a chemical change amount of energy transferred per gram or per mole is commonly called the heat of reaction $\left(\Delta \text{H}\right)$ .

Conclusion

For combustion reactions, the heat of reaction is negative and is also referred to as heat of combustion.