Solutions: Solute, Solvent & Precipitation

• Solute refers to the substance that dissolves in a mixture, typically present in a smaller amount.
• Solvent is the substance in which the solute dissolves.

Types of Solutions:

• Unsaturated Solution: Does not contain the maximum possible amount of solute for a given temperature and pressure.
• Saturated Solution: Contains the maximum possible amount of solute for a given temperature and pressure and exists in equilibrium between the solute and solvent.
• Supersaturated Solution: Contains more solute than can exist in equilibrium at a given temperature and pressure.
• More solute can be added to a saturated solution by heating it.
• If this solution is cooled slowly without disturbance, it may retain an excess of solute, becoming supersaturated.
• Supersaturated systems are unstable; any disturbance causes the excess solute to precipitate out, leaving a saturated solution.

Precipitation

• Precipitation reactions involve the formation of an insoluble compound, called a precipitate.
• This occurs when mixing two different solutions, each contributing an ion to the precipitate.
• A precipitation reaction happens when one or more reactants combine to produce an insoluble product.
• In most cases, the precipitate (solid formed) falls to the bottom of the solution.
• Whether it falls depends on the density of the precipitate.
• It sinks if denser than the rest of the solution or floats if less dense.

Decantation

• Decantation is a physical method for separating heterogeneous mixtures.
• These can be formed by a liquid and a solid or by two liquids.
• It is necessary to allow the mixture to sit so that the solid settles (sediments), descending and allowing extraction by gravity.

Explore the basics of solutions: solute, solvent, and types including unsaturated, saturated, and supersaturated. Understand precipitation reactions and how they lead to the formation of a precipitate. Learn how temperature affects saturation and the instability of supersaturated solutions.