25 ml of diluted unknown acid solution to 100ml beaker by using 25 volumetric pipet. 10ml of deionized water and 3 drops of phenlpthalin indicator the beaker labeled as 3. Potentiometric titration acid solutions 125 ml of NaOH was obtaining in a beaker and 50 ml of NaOH transfer to buret the tip and the meniscus is at below 0 ml. one magnetic stirring bar placed in a beaker contain one of the known solution on a stir. The pH recorded by using pH electrode before adding NaOH.
After the mixture was heated, there was solid on the bottom and liquid on the top of the flask. The set up was let cool to room temperature. Next, we decanted the mixture in to a clean 100 ml beaker. We rinsed the remaining solid with 10 ml of DCM and swirled the mixture. The mixture was decanted again in to the same beaker.
The normality of the unknown base is calculated after the solution has reached the end point. The amount of substance being delivered is calculated in units of equivalents per litre using the formula: VaNa = VbNb Experimental In order to titrate the acid with the unknown base, a solution of the acid was prepared. 5.1722 (±10%)g of potassium hydrogen phthalate acid is obtained using a weighing boat and transferred into a volumetric flask containing 250mL of boiled distilled water. Volumetric flask was shaken several times in order to assist the powder to dissolve. Once dissolved, 24.9734 (± 0.0045)mL of acid was pipetted into an Erlenmeyer flask along with 25mL of cool (recently boiled) distilled water.
Mix using a plastic pipette. f After 10 seconds, use the plastic pipette to place one drop of the mixture on the first drop of iodine. The iodine solution should turn blue-black. Squirt the rest of the solution in the pipette back into the test tube. g Wait another 10 seconds.
After which time, 2.1 mL of 30% hydrogen peroxide was added slowly followed by sodium hydroxide until a pH of 8 was observed. 20 mL of H20 and 10 mL diethyl ether were added to the flask. The contents were separated and the aqueous layer was rinsed with four 10mL portions of ether followed by 15 mL of sodium bicarbonate. The ether layer was dried with granular magnesium sulfate and then the solvent was removed by evaporation under reduced pressure. Lastly, the final product was analyzed by mass spectrometry and HNMR.
8. Placed the remaining mixture, containing sand, benzoic acid and table salt into beaker and added 50mL of distilled water. 9. Set up the beaker stand and burner fuel and heated the beaker of solids and water to near boiling. Stirred the mixture to make sure all soluble material dissolves.
4. Make sure you set the data collection system to Absorbance at wavelength = 635 nm. 5. Measure 100 mL of distilled water into a 250 mL beaker. Add two drops of food coloring to the beaker of distilled water and mix thoroughly.
Procedure: 1. Pour 50.0 mL of 2M HCl into a 8-or pressed polystyrene cup. Label the cup “Acid”. 2. Continue to pour 51.0 mL of 2M NaOH into a clean, dry 150-mL beaker.
Equipment List * Boiling Tube * 10 cm3 1mol dm-3 Hydrochloric Acid (HCL) * 15 cm3 1mol dm-3 Sodium Hydroxide (NaOH) * pH and Temperature Probes * Data Logger * Measuring Cylinder ‘ * Boiling Tube * Teat Pipette Method * Add 10ml of Hydrochloric acid, measured in a measuring cylinder, into a boiling tube. * Into a data logger, plug in both pH and temperature probes and switch on data logger. * Put in both the probes and measure both the temperature and pH before adding any other substances. * Add 1cm3 of Sodium Hydroxide, measured in a measuring cylinder, to the Hydrochloric acid, and
Extraction and Drying: Using a separatory funnel, the cooled filtrate was extracted with 10ml of methylene chloride. After shaking our mixture, we broke and dried our emulsion by slowing passing the lower layer through a cotton ball layered with anhydrous magnesium sulfate. The extraction process was repeated 2 more times for maximum collection of the organic layer. Distillation: The extracts were poured into a 50ml round bottle flask and connected to a simple distillation apparatus. To obtain the caffeine, the methylene chloride was removed from the extract, leaving us with our solid caffeine residue.