CHEMISTRY OF SOLUTIONS
A solution is a - mixture of 2 or more substances in a single phase. One constituent is usually regarded as the SOLVENT and the others as SOLUTES.
Solutions are homogeneous mixtures of two or more pure substances.
In a solution, the solute is dispersed uniformly throughout the solvent
PARTS OF A SOLUTION
SOLUTE – the part of a solution that is being dissolved (usually the lesser amount
SOLVENT – the part of a solution that dissolves the solute (usually the greater amount)
Solute + Solvent = Solution
KINDS OF SOLUTION
Dilute - small amount of solute dispersed in the solvent
Concentrated - large amount of solute is dissolved in the solvent
Types of Solutions Based on Solute Concentration
- Hypotonic solutions - (lower solute concentration) to the solution
- Hypertonic solutions- (higher solute concentration) to the solution
- Isotonic solutions - are equal in their solute concentrations. We say that they are isotonic to each other.
SOLUBILITY
Solubility - refers to the maximum amount of solute, expressed in grams, that can be dissolved in 100 g of water at a specific temperature & pressure.
Solubility = Gram of solute
100 g of Water
Soluble - a substance that dissolves in a solvent
Insoluble - a substance that does not dissolve in a solvent (sand is insoluble in water)
Slightly Soluble - a material will be sparingly soluble if the amount which can be dissolved in 100ml of solute ranges between 0.1g to 1g.
SOLUBILITY IN WATER
Immiscible - two liquids that are insoluble (Oil & Vinegar)
Miscible - two liquids that are soluble in each other (Water & Alcohol ; Water & Antifreeze)
Slightly / Partly Miscible – two liquids are slightly soluble ( Water & Ether ; Alcohol & Oil )
Degree of Saturation
Saturated solution
- Solvent holds as much solute as is possible at that temperature.
- Undissolved solid remains in flask.
- Dissolved solute is in dynamic equilibrium with solid solute particles.
- Contains the maximum amount of solute dissolved.
NaCl = 36.0 g/100 mL water
Unsaturated Solution
- Less than the maximum amount of solute for that temperature is dissolved in the solvent.
- No solid remains in flask.
- Can still dissolve more solute (for example 28.0 grams of NaCl/100 mL)
Supersaturated
- Solvent holds more solute than is normally possible at that temperature.
These solutions are unstable; crystallization can often be stimulated by adding a “seed crystal” or scratching the side of the flask