Lecture Four covers the following points:-


- Concentration unites

Method of Calculation



Methods for expressing the concentration of standard solutions:




The concentration of standard solutions are generally expressed in units of either molarity M or normality N .



Molarity



 It is the number of gram moles of reagent that is contained in one liter solution. (mol/L)

 Molarity M = No. of mole / Volume ( L)



 M = No. of mole / Volume ( L)

 No. of mole = Wt./ M. Wt.

 M= Wt. / [M. Wt. X V ]

 Wt. (g) = M x M.Wt. x V (L)


Normality


• It is the No. of gram equivalents contained in one liter.
• N = No. of gram equivalent / Volume ( L)
• It is the number of milliequivalents of solute in one milliliter of solution.






Strength


• It is the number of grams of solute in one liter solution .
• Wt. (g) = M x M.Wt. x V (L)
• Strenth = M x M.Wt. x 1
• Strenth = M X M. Wt. g/L
• Strenth = N X eq.Wt. g/L



Percent concentration

1- weight percent
2- volume percent
3- weight/volume percent


Part per million ppm


 Cppm = mass solute (mg) / volume solution (L)
 = mg / 1000 g
 = mg / 1000 x 1000 mg
 mg / Kg



Part per billion ppb

 Cppb = ug / 1000 x 1000 x 1000 ug
 1 ppb = 10-3 ppm