1 Chemistry 1211K Lab Report Alexis Hammond 1211K Fall 2019 Friday 2 00 5 00 L 48 06 December 2019 Unknown Organic Acid P5152105 LF 19 2 Introduction Chemistry is a means to understanding what everything is made of and how it came to be down to the most subatomic detail Essentially chemistry is the study of everything in the surrounding of a person Chemistry can be found in the reactions caused by food ingestion or ventilation response to exercise It is how one can see certain light frequencies and not others It is a way to explain the physical and chemical properties of life When viewing an object a person can t help but wonder what it is comprised of Using chemistry we are able to find the identity of many compounds using multiple different strategies For this lab each chemist has the objective to unveil which unknown organic acid has been given In this lab report the identification of an unknown organic acid was determined by comparing the data taken from a few experiments The experiments done to help the search were the melting point experiment solubility experiment and a variety of titrations to establish the equivalent weight and pKa In the quest to find the name of the acid the amateur chemists will learn proper technique and procedure as well as apply chemistry concepts to actual chemical compounds 3 Procedures For melting point the chemist will start by taking 2 3 mm amount into a capillary tube To find an approximate melting point range set the Stuart melting point apparatus to 200 C Place the tube into the apparatus so that the unknown can be seen from the eye viewer Press the start button and observe the unknown melting Next finding the melting point measurement choose a standard closest to the melting point range Place a tube filled with the standard and another with the unknown into heating apparatus Set plateau at 15 C lower than melting point range Record when the sample and standard melt The melting point range is from when the unknown first started to melt until it finished melting Turn apparatus off and allow to cool Next solubility can be determined by weighing out 0 1 grams of the unknown into a test tube If the compound goes into solution at room temperature the solvent is composed of 100 DI water If compound does not become a solution at room temperature try adding heat with a water bath If the test tube s contents dissolve allow the test tube to cool Should the solvent stay dissolved it can be determined as 100 DI water but if crystals form an ethanol DI water mixture should be used Repeating the previous steps with 25 ethanol mixture and 50 ethanol mixture If this doesn t work the chemist should try a 75 ethanol mixture Now for titrations an NaOH solution must be made first The chemist must weigh out 3 6 grams of NaOH into 900 mL of DI water to attain a solution with a molarity of 0 100 M and store it in a closed bottle With KHP titrations cleanse the buret with small amounts of NaOH and fill up to the 0 00 mL line Once done weigh out 0 3 0 5 grams of KHP Dissolve the KHP in 15 20 mL of DI water Use a hot plate to dissolve if needed Add a single drop of phenolphthalein indicator in solution Start to titrate by adding NaOH until the solution turns a very light pink Record the initial and 4 final volumes of NaOH added to the flask The experiment should have three properly done trials As for the HCl titrations cleanse the buret with the NaOH solution and fill to the 0 00 mL line Record initial volume to two decimal places With an automatic pipettor gather 10 00 mL of HCl in an Erlenmeyer flask Add about 20 mL of DI water to flask Add one drop of phenolphthalein indicator into the flask Now start to titrate the solution Once a very faint pink color is reached the chemist can add one more drop to the solution It should lose the color If one more drop is added the solution will have reached its end point Record final volume and repeat steps for two more trials Titrating the unknown organic acid weigh out 0 3 0 5 grams of unknown and dissolve with previously discovered solvent Add a single drop of indicator Once buret is cleaned fill with NaOH Record initial volume and start titrating Record final volume and use the weight of the acid to find the equivalent weight of unknown acid To do computer search input the estimated melting point and equivalent weight with a deviation of about 10 to get a good selection of results Finding pKa weigh out 2 millimoles of the unknown and dissolve in previously selected solvent Add a Teflon coated magnetic stirring bar to the beaker and place on the magnetic stirrer Stirring velocity should be enough to cause a smooth but quick current Carefully place the electrode of a calibrated pH meter in the beaker Clean and fill an buret with NaOH to the 0 00 mL line Record the initial pH and start titrating using 2 mL increments until there is a jump in pH value Allow time for the solution to mix between each round Then start titrating by 1 mL until the pH is at 5 Now add drops to solution until a pH of 9 is reached Lastly add 1 2 mL each time to a pH of 12 to 13 is reached Graph NaOH volume vs pH using Excel 5 Results Table 1 Results of Melting Point Experiment Plateau used in determination of melting point 94 C Melting Point Range for the Standard A Printed Value 98 100 B Experimental Value 99 100 Melting Point for Unknown Acid 107 C Table 2 Results of Solubility Experiment Trial Ethanol 1 2 3 4 0 25 50 75 Solubility Solvent Dissolved at Room Temperature No No No No Dissolved with Heat No No Yes Yes 50 Ethanol 50 DI Water Table 3 Results from KHP Titrations Trial Mass of KHP Moles of KHP Vol NaOH Molarity of NaOH 1 2 3 0 4025 g 0 4495 g 0 4627 g 20 00 mL 22 01 mL 22 98 mL 0 09854 M 0 1000 M 0 09859 M Average Molarity Deviation 0 001971 moles 0 002201 moles 0 002260 moles 0 099 M 0 001 1 6 0 4025 1mol KHP 0 00197091 mol KHP 0 099 M 204 22 g 0 02 L NaOH Table 4 Results from HCl Titrations Trial Vol HCl Moles of HCl Vol NaOH Molarity of HCl 1 2 3 10 00 mL 10 00 mL 10 00 mL 0 001962 moles 0 001969 moles 0 001960 moles 19 82 mL 19 89 mL 19 80 mL 0 1962 M 0 1969 M 0 1960 M Average Molarity Deviation 0 196 M 0 001 0 5 1 mol HCl 1 mol NaOH 0 01989 L NaOH 0 099 M NaOH Table 5 Results …