VPB 112: General Veterinary Biochemistry (1+1)

PREPARATION OF 1000 ml of N/10 HCl ACID SOLUTION

• HCl is a monobasic acid and is aqueous anhydrous.     

                                              Equivalent weight of HCl = Molecular weight / 1 = (1+35.5)  / 1 = 36.5 / 1 = 36.5 = 36 g (approx.)

                                              Specific gravity (of the commercially available HCl) = 1.18 (1.18 g of HCl / 1000 ml) = 1180 g of HCl / 1000 ml

• We know that 36 g of HCl in 1000 ml = 1 N         
• Then, 1180 g of HCl in 1000 ml will be = 1 x 1180 N /36 = 32.78 N   
• But the assay (purity) of the commercially available HCl solution = 36%                                                                          
• Therefore, the actual normality will be =(36/100) x 32.78 = 11.79 N.                                                                 
• We are required to prepare 1000 ml of 0.1N HCl using this above 11.79 N HCl stock solution.
• Therefore, the Volume of Stock (Conc.) HCl required can be calculated by using the equation:   

                    V₁N₁ = V₂N₂  

• Where, N₁ = Normality of the Conc. HCl = 11.79 N
• V₁ = Volume of the Conc.HCl (Unknown)
• N₂ = Normality of HCl to be prepared = 0.1 N
• V₂ = Volume of HCl to be prepared = 1000 ml
• Substituting the Values, we get 11.79 N x V1 = 0.1 N x 1000 ml
• Then, V₁= ((0.1 N x 1000 ml )/11.79N)=8.48ml
• Therefore, 8.48 ml of HCl is diluted with distilled water to make up the volume to 1000 ml.

Procedure

• The Commercially available Conc. HCl is approximately 11.79 N.
• Take 8.4 ml of the above HCl and initially dilute it by slowly adding drop by drop and stirring it in about 500 ml of distilled water.
• Then make up the volume to 1000 ml in distilled water.