Chapter 21, Problem 124SCQ

(a)

Interpretation Introduction

Interpretation:

To predict the number of tin and oxide ions present in per unit cell of tin oxide.

Concept introduction:

The formula for tin oxide is ${\text{SnO}}_{\text{2}}$. Tin has an oxidation number of $+4$ in this compound. ${\text{SnO}}_{\text{2}}$ also known as, cassiterite is the main ore of tin.

Tin oxides crystallizes in a rutile like unit cell in which ${\text{Sn}}^{4+}$ and ${\text{O}}^{2-}$ ions are present. The compound should be electrically neutral.

(b)

Interpretation Introduction

Interpretation:

Check whether it is thermodynamically feasible to transform solid $Sn{O}_2$ into liquid $SnC{l}_4$ by reactionof the oxide with gaseous $HCl$ or not. The equailibrium constant for this raction at ${25}^{0}C$ is to be determined.

Concept introduction:

The free energy change is expressed as,

${\text{Δ}}_{\text{r}}{G}^{\text{°}}=\sum n{\Delta }_f{G}^{\text{°}}\left(\text{products}\right)-\sum n{\Delta }_f{G}^{\text{°}}\left(\text{reactants}\right)$

The positive value of ${\text{Δ}}_{\text{r}}{G}^{\text{°}}$ indicates the thermodynamic unfeasibility of a reaction.

If the free energy change value is known then the equilibrium constant can be determined using the following equation.

$K_{\text{p}}=e^{-\frac{{\Delta }_{\text{r}}{G}^{\circ }}{RT}}$