Experiment Colligative Properties & Osmotic Pressure Karmin Currin 1/19/2014 1:00pm Abstract The purpose of this experiment is to understand and compare the difference of the freezing points between pure solvents in a solution and a non-volatile solute. Secondly, osmosis is demonstrated in a permeable membrane in this case a dialysis tubing and a less permeable membrane with a much harder shell like the egg. Experiment and Observation Starting with Part I of this experiment I gathered together all my items I needed. Small rubber band, salt, tap water, distilled water, 1/8 teaspoon measuring spoon, crushed ice, beaker 100 mL plastic, stopwatch-digital, test tube 13 x 100 mm, digital thermometer, well plate-24. First I made a water bath by filling the 100 mL beaker with cool tap water.
Rinse the tube with distilled water several times. Add about 1 mL of the solution to be measured. Tilt and turn the cuvette so that the solution has contact with all the surfaces. Discard this solution and repeat this rinse once more. Fill the cuvette about 3/4 full of the solution you wish to test.
A flame test was then conducted and the identity of the cation was determined. To determine the anion, the anion had to be separated first from the cation in the unknown compound. To do this, 0.1 grams of the unknown compound and 0.5 grams of sodium carbonate had to be boiled in 5 mL of distilled water. Once the solution boiled for 10 minutes, the precipitate was centrifuged out and the anion solution was left. 0.1 M silver nitrate was added to the anion solution and a precipitate was formed.
The pH recorded by using pH electrode before adding NaOH. The solution titrated by 2 ml of NaOH each time and the pH recorded until the color change. These steps were done for the two known solutions and the unknown solution. Part 2 10 ml of vinegar placed in 100ml volumetric flask and deionized water added until the mark. The solution transferred in 150 ml beaker labeled as beaker #1.
Allow the crystals to dry for 1 week then, weigh it, take a MP, and calculate the % yield. * Assemble the apparatus for reflux using the diagram (see figure 1), place boiling chips or a stirring bar in the bottom of the flask. * Weigh 2grams of finely ground nutmeg and combine with 10ml of diethyl ether in a 50ml round bottom flask. * Place a heating mantle under the round bottom, turned on and the heat was slowly adjusted until the mixture starts to boil for 45minutes, then let cool to room temperature by sitting it on the lab bench. * Pour a little ether over the nutmeg residue on the filter paper so that any Diethyl ethanol traces clinging to it is washed down and mixed with the filtered liquid underneath.
Using a burette, run 5.0 cm3 of 0.100 mol dm-3 peroxodisulphate solution into a 100 cm3 beaker. Add 45 cm3 of distilled water, from a burette, stir gently to mix. 2. Using burettes, measure out 15 cm3 of each of the 0.500 mol dm-3 potassium iodide, 3 cm3 of 0.010 mol dm-3 sodium thiosulphate solutions and 2.0 cm3 of starch solution into the second 100 cm3 beaker. 3.
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.
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.
The 15 M NH4OH was added drop wise until a color change occurred, or until 20 drops were added. An additional 10 drops of 15 M NH4OH were then added to each solution. Again, 5 centrifuge tubes were labeled for the same 5 cations and 20 drops of each solution were added to the appropriate centrifuge. HCl was also added to a 50 mL beaker. The Nichrome wire loop was dipped in the HCl solution and placed over the Bunsen burner to disinfect it.
What should this contain? j Count up how many iodine drops you have used, each one equals 10 seconds of reaction time. k Repeat the whole procedure with another of the pH buffers or pool your results with others in your class. l Collect repeat data if there is time. m Plot a graph of time taken for starch to break down against pH.