1.0 SCOPE
This standard testing procedure is suitable for the Standardisation of Sodium Hydroxide Solution.
2.0 RESPONSIBILITY
The expert and trained chemist are responsible for following this procedure. The technical manager is responsible for implementing this procedure.
3.0 REQUIREMENTS
3.1 Apparatus: NA
3.2 Glassware
3.2.1 Conical Flask (250 ml)
3.2.2 Burette-50 ml
3.2.3 Pipette-10 ml,25 ml
3.2.4 Measuring cylinder-100 ml
3.3 Reagent
3.3.1 Sodium hydroxide solution to be standardized
3.3.2 Previously dried Potassium hydrogen phthalate
3.3.3 Phenolphthalene indicator
4.0 PROCEDURE
4.1 standard potassium hydrogen phthalate solution
Dry about 25 g of potassium hydrogen phthalate ( HK.CsHIJOI ) at 105°C for 04 hours or 1300 for 01 hour and cool.
4.2 Mass accurately (to within 0.0001 g) between 0.7 and 0.9 g of KHP into a tared plastic weighing dish.
Note: If the mass of KHP taken exceeds 0.9 g, the titration may require more than 50 mL of titrant, making it necessary to refill the buret and thereby introducing two more buret reading errors.
4.3 Use a plastic wash bottle with distilled water to rinse the sample from the weighing boat and transfer it quantitatively to the clean 250 mL flask.
4.4 Add enough water to bring the total volume to about 50 to 75 mL (Remember - we are concerned only with the amount, in moles, of acid; the exact volume is not important). Swirl the flask and rinse down the sides of the flask to dissolve the sample.
4.5 Add 4 or 5 drops of phenolphthalein indicator to the flask.
4.6 Rinse the buret 2 or 3 times with small portions of NaOH solution before filling it. Make certain that all air bubbles have been flushed from the tip before taking the initial volume reading (the last lab class may have left the burets filled making the previous step unnecessary, however, you should check for bubbles and a full tip). When reading the buret, use a buret reading card, avoid parallax (ask your teacher to demonstrate if you don’t know this concept), and estimate each reading to the closest 0.01 ml.
4.7 Titrate the sample of KHP until the faint, pink endpoint is reached. Add the titrant rapidly at first, but slowly later as the endpoint is approached as indicated by the less rapid disappearance of the pink color as the added titrant mixes with the solution in the flask. Rinse down the sides of the flask to make sure that any splattered NaOH gets a chance to react. Add the final increments dropwise, or even in half-drops washed from the buret tip with a few drops of water. The endpoint has been reached when a faint pink color persists throughout the mixed solution for about 30 seconds. Dissolving CO2 will produce carbonic acid, which will neutralize the excess NaOH and turn the phenolphthalein colorless if the titration is too far overrun. Exercise care to avoid overshooting the endpoint (intense pinkish-red color). If you do accidentally overshoot the endpoint, weigh a fresh sample of KHP and repeat the titration.
4.8 Titrate two (or three, if time permits) separate weighed samples of KHP.
4.9 Calculate the moles of KHP, NaOH, and the molarity of the NaOH. Average the molarities from the different trials and calculate the percent error.
4.10 Note down the titration value.
5.0 CALCULATION
N= Weight of KHP(Std. Solu.) 1000/Vol. of NaOH used (204.2)
6.0 REVISION/CHANGE HISTORY NA
7.0 ATTACHMENTS
·Appendix 1: FLOW CHART FOR SODIUM HYDROXIDE STANDARDISATION
8.0 REFERENCES: IS 2316:1990
END OF THE DOCUMENT
You may like to read these links:
1. List of All SOPs and Documents for the Chemistry Laboratory
2. List of All SOPs and Documents for Quality Control
3. List of All SOPs and Documents For Quality Assurance Dept.
4. List of SOPs and Documents Required to Achieve NABL Accreditation
2.
2.1.
2.2.
2.3.
2.3.1.
2.3.2.
Hi. I’m Writer of Researchsop.com. ’ ’ Please share these SOPs to all concern pharma people for their development. I like to fullfill the need of curious people. These things inspire me to make things looks better.
0 comments:
Post a Comment