Why is the solubility of KHTar greater in a 0.10M NaNO3 solution than in distilled water?
NaNO3 increases the ionic strength of the solution and most compounds have increased solubility with increased ionic strength.
The solubility of KHTar (potassium hydrogen tartrate) is greater in a 0.10 M NaNO3 (sodium nitrate) solution compared to distilled water due to the common ion effect.
The common ion effect occurs when a compound is dissolved in a solution that already contains one of its constituent ions. In this case, KHTar contains the potassium ion (K+) and the hydrogen tartrate ion (HTar-). When KHTar is dissolved in water, it dissociates into its respective ions: K+ and HTar-.
In distilled water, there are no additional potassium ions present. However, in a 0.10 M NaNO3 solution, there are already sodium ions (Na+) present from the dissociation of sodium nitrate (NaNO3). Since both sodium ions and potassium ions are positively charged, they compete for space in the solution.
The presence of the additional potassium ions from the sodium nitrate solution causes a shift in the equilibrium of the dissolution reaction of KHTar, pushing it to favor the formation of more KHTar molecules. This effectively increases the solubility of KHTar in the sodium nitrate solution compared to distilled water.
The solubility of a substance refers to the maximum amount of solute that can dissolve in a given amount of solvent, usually expressed in terms of grams of solute dissolved in 100 milliliters (or some other specified volume) of solvent.
In this case, the solubility of KHTar (potassium hydrogen tartrate) is greater in a 0.10M NaNO3 (sodium nitrate) solution compared to distilled water due to a phenomenon called common ion effect.
The common ion effect occurs when the solubility of a salt is decreased by the presence of a common ion from another compound. In this case, both KHTar and NaNO3 contain potassium ions (K+). When KHTar is dissolved in distilled water, it dissociates completely into its constituent ions - K+ and HTar- (hydrogen tartrate ion).
However, when KHTar is dissolved in a NaNO3 solution, the presence of additional K+ ions from the NaNO3 compound reduces the solubility. This is because the concentration of K+ ions is already higher due to the dissolved NaNO3, and according to Le Chatelier's principle, the equilibrium of the dissolution reaction is shifted towards the solid KHTar, resulting in a decrease in solubility.
Overall, the increased concentration of K+ ions in the NaNO3 solution decreases the solubility of KHTar, meaning that less KHTar can dissolve in the solution compared to distilled water.