Assay of NaOH Solution - Lab Procedure for Determining Sodium Hydroxide Content

This essay discusses the assay of NaOH solution, focusing on the two-step titration process involving NaOH and HCl for determining the concentration of NaOH. Detailed procedures, chemical factors, and calculations for both titration steps are explained in depth. The analysis also includes the rationale behind using BaCl2 in the first titration step. The primary aim is to accurately determine the NaOH content in the solution for quality control purposes in pharmaceutical chemistry.

• NaOH solution
• Titration process
• Chemical analysis
• Laboratory procedure
• Sodium Hydroxide

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1. ASSAY OF NAOH SOLUTION Lecturer Luma Amer Department of Pharmaceutical Chemistry/Collage of pharmacy 1 1 st st stage: stage: 2 2st stlab. lab.

2. Lab. 2 Assay of NaOH Solution NaOH (secondary standard solution) because it is a hygroscopic , so in BP. , NaOH solution contains not less than 97.5 %(w w) of total alkali calculated as NaOH , and not more than 2.5 %(w w) of Na2CO3. Chemical formula NaOH ,molar mass 40.00 g/mol. Very soluble in water; freely soluble in ethanol , Sodium Hydroxide occurs as a white lumps having various shapes including pellets, flakes, and rods, or as a white powder. Sodium Hydroxide solution is strongly alkaline.

3. so we have to do titration of two step, and we have to add BaCl2 in the first titration, why?

4. procedure 1. First titration 0 10 20 1 N HCl 30 40 NaOH +HCl NaCl + H2O Turbid pink sol. Turbid colorless Calculate V1 V of HCl NaOH 50 10 ml of NaOH sol. + 5 ml BaCl2 sol. + 5 ml D.W.+ 1-2 drop (ph.ph.)

5. 2. Second titration 0 10 20 1 N HCl 30 Na2CO3 + 2HCl 2NaCl + H2O + CO2 Bluish violet yellow Calculate V2 V of HCl for Na2CO3 V T = V1+ V2 40 50 To the same conical flack add 3 drop of BPB

6. Chemical Factor : it is the weight of substance which is chemically equivalent to 1ml of standard solution. Calculation of the chemical factor: 1.first titration (for the reaction of HCl with NaOH): NaOH +HCl NaCl + H2O 1eq wt. NaOH 1eq wt. HCl 1 40g NaOH 1L 1N HCL (standard sol.) N = eq wt./V(l) 40/1000g NaOH 1ml of 1N HCl 0.04g NaOH 1ml 1N HCL chemical factor for first titration.

7. 2. Second titration ( for the reaction of 2HCl with Na2CO3): 2HCl + BaCO3 BaCl2 + H2O + CO2 2HCl + Na2CO3 2NaCl+ H2O + CO2 2eq wt. of HCl 1M wt. of BaCO3 1 M wt. Na2CO3 1 M wt. Na2CO3 2 eq wt. of HCl 1/2 M wt. Na2CO3 1 eq wt. of HCl (106) Na2CO3 1L of 1N HCl 53 g Na2CO3 1L of 1N HCl 53/1000 g Na2CO3 1ml of 1N HCl 0.053 g Na2CO3 1ml of 1N HCl (chemical factor for the second titration).