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Moderate

Enthalpy of Reaction for the Dissolution of Sodium Nitrate

APCHEM-EXXJYH

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, which of the following is $\Delta$ ${H}^{\circ}_{rxn}$?

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

Exothermic.

$\Delta$ ${H}^{\circ}_{rxn} = -894.69 \ \text{kJ/mol}$

B

Endothermic.

$\Delta$ ${H}^{\circ}_{rxn} = 894.69 \ \text{kJ/mol}$

C

Exothermic.

$\Delta$ ${H}^{\circ}_{rxn} = - 0.31 \ \text{kJ/mol}$

D

Endothermic.

$\Delta$ ${H}^{\circ}_{rxn}= 0.31 \ \text{kJ/mol}$