Chapter 4, Problem 4.20NP

(a)

Interpretation Introduction

Interpretation:

The enthalpy of combustion of ethanol needs to be calculated under the given conditions.

Concept Introduction:

Combustion is a thermochemical reaction in which a substance burns in the presence of excess oxygen to produce carbon dioxide and water.Combustion reactions are exothermic in nature i.e. it is accompanied by the release of energy.

(b)

Interpretation Introduction

Interpretation:

The enthalpy of formation of ethanol needs to be calculated under the given conditions.

Concept Introduction:

A thermochemical equation is a balanced stoichiometric equation which depicts the change in the reaction enthalpy i.e. the magnitude and sign of ΔH is added to the right of the equation. The standard enthalpy changefor a reaction ${\text{ΔH}}^{\text{0}}$ is given in terms of the difference in the standard enthalpy of formation of the products and that of reactants.

i.e. $\Delta {\text{H}}^0\text{ = }{\displaystyle \sum {\text{n}}_{\text{p}}{\text{ΔH}}_{\text{f}}^{\text{0}}}\text{(products) - }{\displaystyle \sum {\text{n}}_{\text{r}}{\text{ΔH}}_{\text{f}}^{\text{0}}}\text{(reactants) ------(1)}$

Here, n_p and n_r are the number of moles of the products and reactants