Molality and Normality

 Molality 
Many physical properties are related to solution concentration expressed as Molality m, the number of moles of solute dissolved in one kilogram of solvent. The defining equation is:

                            mol solute
                  m  =   ------------
                            kg solvent

If a solution contain 0.755 mole of acetic acid per kilogram of water, we identify it as 0.755 m

CH₃COOH. In a calculation setup, we would write "0.755 mol CH₃COOH/kg H₂O".

 

Normality
It is defined a one gram equivalent of a solute per litre of solution. The definition of a gram equivalent varies depending upon the type of chemical reaction. It is critical to note that normality measures a single ion which takes part in an overall solute. For example , one could determine the normality of hydroxide or sodium in an aqueous solution of sodium hydroxide.But the normality of sodium hydroxide has no meaning. However it is often used to describe solutions of acids or bases.So in these cases Normality refers to H⁺ or OH^- 


In acid base chemistry, Normality is used to express the concentration protons or hydroxide ions in a solution. In redox solutions, normality measures the quantity of oxidizing or reducing agent that can accept or furnish one mole of electrons.