Chapter 23, Problem 23.81P

Interpretation Introduction

Interpretation:

Values of, $\Delta H_{rxn}^o$$\Delta S_{rxn}^o$ and $\Delta G_{rxn}^o$ have to be calculated for the reaction $Mg\left(s\right)+\text{ 2 HCl}\left(aq\right)\underset{}{\rightleftharpoons }{H}_2\left(g\right){\text{ + MgCl}}_2\left(aq\right)$.

Concept Introduction:

Enthalpy$\left(H\right)$: It is the total amount of heat in a particular system.

The value of standard enthalpy change ${\text{ΔH}}^{\text{ο}}$ of the given reaction is calculated by the formula,

  ${\text{ΔH}}_{rxn}^{\circ }\text{=}{{\displaystyle \sum {\text{n}}_{\text{p}}{\text{ΔH}}_{\text{f}}^{\text{ο}}}}_{\left(\text{products}\right)}-{{\displaystyle \sum {\text{n}}_{\text{r}}{\text{ΔH}}_{\text{f}}^{\text{ο}}}}_{\left(\text{reactants}\right)}$

Where,

${\text{ΔH}}_{\text{f}}^{\text{ο}}$ is the standard enthalpies of formation.

n is the number of moles.

Entropy$\left(S\right)$: it is used to describe the disorder. It is the amount of arrangements possible in a system at a particular state.

Value of $\Delta S_{rxn}^o$ can be calculated by the equation:

  $\Delta S_{rxn}^o\text{= }S°\left[\text{products}\right]-S°\left[\text{reactants}\right]$

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by $\Delta G$. Value of $\Delta G_{rxn}^o$ is determined as follows,

  $\Delta G_{rxn}^o=\Delta H_{rxn}^o-T\Delta S_{rxn}^o$