Question

Is sodium benzoate soluble in NaOH, NaHCO3

Answer 1

It is water soluble so is also soluble in aqueous solutions of NaOH or NaHCO3.

Answer 2

Answer:

It's slightly soluble in an aqueous solution of $NaHCO_{3}$, and almost insoluble in an aqueous solution of NaOH.

Explanation:

Sodium benzoate comes from benzoic acid, which is a weak acid. It means that in an aqueous solution benzoic acid does not ionize easily to form the ions $H_{3}O^{+}$ and $C_{7}H_{5}O_{2} ^{-}$

It also implies, according to the Le Châtelier's principle, that the ion $C_{7}H_{5}O_{2}^{-}$ tends to form the acid $C_{7}H_{6} O_{2}$ more easily. It can be seen in the following equation:

$C_{7}H_{6} O_{2}$  ⇔ $C_{7}H_{5}O_{2}^{-}$  + $H_{3}O^{+}$

In an aqueous solution, the equilibrium shifts to the left, thus letting water dissolve sodium benzoate.  But why? Because water in that case would produce enough $H_{3}O^{+}$ ions to facilitate the disolution of sodium benzoate. It's shown by its solubility in water at 15°C (62.78g/100mL, according to Wikipedia).

In contrast, the presence of NaOH or $NaHCO_{3}$, both chemical species producing the $OH^{-}$ ions in aqueous solution, would make the equilibrium shift to the right because it would be a higher need of $H_{3}O^{+}$ ions to offset the presence of $OH^{-}$.

However, the effect of NaOH is not the same due to $NaHCO_{3}$, because the first is a strong base and the other is a weak one. Thereby it is reasonable to think that solubility of sodium benzoate is greater in water than in $NaHCO_{3}$ and NaOH.

Solubility in water > solubility in  $NaHCO_{3}$> solubility in NaOH.