Solutions

•Definitions

•A Solution is a homogeneous mixture of two or more substances
                            OR

•A solution is a homogeneous mixture of solute and solvent      
                   

                           OR

A solution is a homogeneous mixture of two substances but consisting of one phase.
•Homogeneity: something evenly distributed

•Heterogeneity: something not distributed evenly in space; a clump or cluster.

•A Solute is dissolved in a Solvent.

–solute is the substance being dissolved

–solvent is the liquid in which the solute is dissolved–an aqueous solution has water as solvent

•Binary solution: A homogeneous mixture consisting of one phase and containing only two components i.e. one solute and one solvent e.g. Solution of NaCl in water.

•Dilute Solutions:
 A solution containing relatively small quantity of solute as compared with the amount of solvent.

•Concentrated Solution: A solution containing large amount of solute in the solution than that in dilute solution.

•Un-saturated solution: a solution in which more solute can be dissolved at a given temperature is called as an unsaturated solution.
•A Saturated solution is one where the concentration is at a maximum - no more solute is able to dissolve at a given temperature.

–A saturated solution represents an equilibrium: the rate of dissolving is equal to the rate of crystallization.  The salt continues to dissolve, but crystallizes at the same rate or under these condition the number of molecules leaving the solute is equal to the number of molecule returning to the solid phase i.e. solute.

•Types of Solutions: Based on physical states of solute and solvent:

•      BASED ON PARTICLE SIZE:•Solution systems or dispersed systems are those system in which one substance ( i.e. solute) is dispersed through an other phase ( i.e. solvent) called continuous phase. So the solute is called dispersed phase or dispersoid and solvent as solvent as continuous phase
•Solutions may be categorized on the basis of dispersion as follows:

•Ultra filtration is a separation process using membranes with a pore sizes in the range of 0.1 to 0.001 micron. Typically, ultra filtration will remove high molecular weight substances, colloidal materials and organic polymeric molecules. Low molecular weight organics and ions such as sodium, calcium, magnesium and sulfates are not removed.