Key Difference – Saturated vs Supersaturated Solution
Let us first briefly look at the concept of saturation before moving on to a complex analysis of the difference between Saturated and Supersaturated Solution. Solutions are made by dissolving a solute in a solvent. The two chemical properties of “saturation” and “supersaturation” in solvents mainly depend on the solubility of the solute in the solvent. At a given temperature, the solubility of a solute in a particular solvent is a constant (Q).
Q is defined as the ion product of the solute.
Example: Solubility of AgCl in water (QAgCl) = [Ag+][Cl-]
Generally, if we keep on adding the solute into the solvent, there is a maximum quantity which we can add dissolve in the solvent. After a certain limit, the solute starts to precipitate in the solvent. It becomes a supersaturated solution after this limit. It is called a saturated solution when we can dissolve the solute with no formation of a precipitate.
The key difference between Saturation and Supersaturation is that, Saturation is the state at which a solution of a substance can dissolve no more of that substance, and additional amounts of it will appear as a separate phase while supersaturation is a state of a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances.
What is a Saturated Solution?
There is a very limited number of compounds which are infinitely soluble in a solvent; which means, we can mix the solute in the solvent in any proportion to dissolve without forming a precipitate. However, most of the solutes are not infinitely insoluble; they form a precipitate if you add more solute into the solvent.
Saturated solutions contain the maximum number of solute molecules it can dissolve with no precipitation.
What is a Supersaturated Solution?
Supersaturated solutions are formed if you add additional solute to the saturated solution. In other words, it is the condition in a saturated solution, when you add some additional quantity of solute into the solution. Then it will start to form a precipitate in the solution because the solvent has exceeded the maximum quantity of solute molecules it can dissolve. If you raise the temperature of the solvent, you can make a saturated solution by dissolving the solute molecules.
What is the difference between Saturated and Supersaturated solution?
Definition of Saturated and Supersaturated Solution
Saturated Solution: At a particular temperature, a solution is said to be a saturated solution, if it contains as much as solute molecules which the solvent can hold.
Supersaturated Solution: At a particular temperature a solution is said to be a supersaturated solution if it contains more solute molecules it can dissolve.
For saturated solutions; Q = Ksp (No precipitation)
For supersaturated solutions; Q > Ksp (Precipitate will form)
Q = solubility (reaction quotient)
K sp= Solubility product (mathematical product of dissolved ion concentrations raised to the power of their stoichiometric coefficients)
Example: Consider dissolving Silver Chloride (AgCl) in water.
AgCl – Solute and Water – Solvent
AgCl has dissolved in water A large quantity of AgCl has dissolved in water.
The solution is clear The precipitate is clearly visible
Q= [Ag+][Cl-] = Ksp Q= [Ag+][Cl-] > Ksp
[Ag+]= Concentration of Ag+ in water
[Cl-] = Concentration of Cl- in water
For AgCl, Ksp = 1.8 ×10–10 mol2dm-6
How can we make saturated and supersaturated solutions?
Both saturated and supersaturated solutions are formed when you keep on adding a particular solute into a solvent. At a given temperature, first, it forms an unsaturated solution and then, a saturated solution and finally the supersaturated solution.
Example: Dissolving salt in water
Unsaturated Solution: Less amount of salt in water, clear solution, no precipitation.
Saturated Solution: The maximum amount of salt is dissolved in water, Colour of the solution slightly changes, but no precipitation.
Supersaturated Solution: More salt is dissolved in water, Cloudy solution, precipitation is visible.