| 0.1M Ethanolic Sodium Hydroxide |
| 1.0 Scope: This procedure is applicable for preparation and standardization of 0.1M Ethanolic sodium hydroxide solution. 2.0 Apparatus: 2.1 1000 ml volumetric flask 2.2 250 ml glass-stoppered conical flask 2.3 100 ml graduated burette 2.4 100 ml volumetric flask 3.0 Reagents soln. preparation: 3.1 Sodium hydroxide AR grade 3.2 Benzoic acid AR grade 3.3 Thymolphthalein solution 3.4 Ethanol (95%v/v) 4.0 Preparation of Reagents: 4.1 Thymolphthalein solution: Take 0.1 gm of 100mg of Thymolphthalein in ethanol C2H6O and dilute to 100.0 millilitre. To read this SOP click here Preparation and Standardization of 0.1M Hydrochloric acid. 5.0 Preparation: Dissolve about 4.2 g of sodium hydroxide in 5 ml of purified water and add sufficient aldehyde-free ethanol to produce 1000 ml. Allow the soln. to stand in a tightly-stoppered bottle for 24 hours. Then quickly decant the clear supernatant liquid into cleaned and dried plastic bottle. 6.0 Standardization: Weigh accurately and transfer about 0.6 g of Benzoic acid, previously powdered and dried about 120oC for 2 hours to a 250 ml glass stoppered conical flask and dissolve in mixture of 30 ml of ethanol (95%) and 6 ml purified water. Add 0.2 ml of thymolphthalein solution as indicator and titrate with the 0.1 M ethanolic sodium hydroxide solution until a permanent pink colour is produced. Each ml of 0.1M (NaOH) is equivalent. to 0.01221 gm of C7H6O2. 7.0 Calculation: M= W X 0.1 / V X 0.01221 Where: M = molarity of 0.1M ethanolic sodium hydroxide W = weight of benzoic acid in g V = volume of 0.1M ethanolic sodium hydroxide in ml 8.0 Storage: Store in a transparent glass stoppered bottle |