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Moderate

Entropy of Reaction for the Dissolution Sodium Nitrate

APCHEM-L7EUJU

Sodium nitrate is soluble in water at $25^{\circ}C$ as evidenced by:

$$NaNO_3 \rightarrow {Na}^{+}_{(aq)}+ {NO}^{-}_{3 (aq)}$$

Using the thermodynamic data below, what is $\Delta$ ${S}^{\circ} _{rxn}$?

Reactant / Product $\Delta H^{\circ}$ $_{f} $ (kJ / mol) $\Delta S^{\circ}$ $_{f} $ (J / mol)
NaNO$_{3(aq)}$ -447.5 205.4
Na$^+$ $_{(aq)}$ -240.34 58.45
NO$_3$ $^-$ $_{(aq)}$ -206.85 146.70
A

$\Delta$ ${S}^{\circ} _{rxn} = 0.25 \text{ J/mol}$

Entropy has increased.

B

$\Delta$ ${S}^{\circ} _{rxn} = - 0.25 \text{ J/mol}$

Entropy has decreased.

C

$\Delta$${S}^{\circ} _{rxn} = 410.55 \text{ J/mol}$

Entropy has increased.

D

$\Delta$ ${S}^{\circ} _{rxn}= -410.55 \text{ J/mol}$

Entropy has decreased.