The buret is filled to a point above the "0" mL mark with NaOH solution. In order to fill the tip of the buret with liquid, the solution is drained out of the bottom until the meniscus lies between the "0" and "1" mL marks. The initial buret reading can now be recorded to the nearest 0.01 mL. If you have any doubts as to your ability to read the buret correctly, ask your instructor to check your initial reading. Standardization of NaOH solution Accurately weigh out a sample of approximately 0.3-0.4 g of primary standard potassium hydrogen phthalate, KHPh, which has been previously dried at 120°C.
1.25mL of acetic acid and ferric chloride mixture was added to 2.5mL of the pure extract. Occurrence of blue-green color indicates the presence of glycosides. Test for Saponins. 10mL of distilled water was added to 5 mL of the pure extract the mixture was shaken in a graduated cylinder for 15minutes. Occurrence of layer of foam or bubbles indicates presence of saponins.
Using these solutions, aqueous solutions of the ions [Cu(H2O)n(NH3)6-n]2+ ( n= 1 to 6) were prepared as follows: 1.) To 5 cm3 copper solution (a), solid ammonium nitrate was added until saturated. Then 5 cm3 of 1 mole dm-3 ammonium hydroxide was added slowly. Further solid ammonium nitrate was added to resaturate. 1 cm3 of this solution was diluted to 25 cm3 with 2 mole dm-3 ammonium nitrate.
Standardization of NaOH solution The prepared solution in part A was used to determine the acidity of the two different brands of soft drinks. But before it, the NaOH solution was standardized first. A 0.15 g of potassium acid phthalate was dissolved in 0.05 L of water in an Erlenmeyer flask. Afterwards, 3 drops of phenolphthalein was added. A 50 mL buret was obtained and was washed with NaOH solution.
SOLUBILITY AND SOLUBILITY PRODUCT OBJECTIVE In this experiment you will determine the solubility and solubility product of a sparingly soluble salt, potassium hydrogen tartrate, and also in four solutions containing a common ion. INTRODUCTION When a salt of low dissolubility dissolves in water, equilibrium is established between the solid solute and the dissolved ions. There are two terms used in discussing this condition. The first is solubility, which is the maximum amount of salt that will dissolve in a given amount of solvent (usually water) at a specified temperature. Solubility is usually expressed in units of molarity (moles/L), but sometimes g solute/ g solvent is used.
Each 0.1M Sodium hydroxide solution that had been rinsed was drain into the waste container located under the hood. 3. The burette was filled with 0.1M Sodium hydroxide solution(prepared prior of this experiment) to 50 ml volume and the burette was clamp vertically(the air bubbles was remove from the tip of the burette by draining the 0.1M Sodium hydroxide into smaller beaker) 4. The 10g or 10ml amount of samples was inserted into 250ml conical flask and with addition of 50ml distilled water 5. Three to five drops of phenolphthalein were added into conical flask 6.
Thus, the acid-base indicator used in this experiment is the phenolphthalein. Besides, phenolphthalein is also a suitable indicator for titration between a strong base and a weak acid. Phenolphthalein is colourless in an acid solution but pink in base solution. Phenolphthalein was added into both original oxalic acid (C2H2O4) and acetic acid (CH3COO) solution before the acid-base titration was carried out. Phenolphthalein is a weak acid and is represent as Hln in the following chemical
Write this down when you start the titration. Next, you must determine the volume of the solution delivered to reach the equivalence point. Next, you will find the moles of base used in the titration: *Note that the volume of base is in L, not in mL Determine number of moles of HCl in flask: If you write the balanced reaction for the neutralization of sodium hydroxide and hydrochloric acid, you will see that the reaction proceeds in a 1:1 fashion. That is, for every hydroxide (OH‐) ion added, it can neutralize exactly one hydronium (H+) ion. This is not always the case for neutralization reactions, and is thus not always the case for acid‐base titrations.
Then the drug content was determined by comparing the absorbance of this solution with standard solution having same concentration. 6.4.8. In vitro drug release studies98: In-vitro release of zolpidem tartarte from pellet formulations was investigated by the Paddle method (Apparatus II). The dissolution medium was 500 mL of 0.01N HCl solution at 37 ± 0.5 °C and the rotating speed was 50 rpm. At certain time intervals, 1 ml of sample was withdrawn and immediately same amount of fresh medium (37±0.50C) was replaced.
The appearance of dark green colour indicated the presence of tannins (Cuilel, 1994). Test for steroids 1g of both extracts were weighed and placed in test tubes. The extracts were dissolved in 2 ml of acetic anhydride and 4 drops of chloroform were added into the test tubes. Then, 2 drops of concentrated sulphuric acid were added. The formation of brownish ring at interface of two liquids and the appearance of violet colour in supernatant layer indicated the presence of steroids glycosides (Cuilel, 1994).