Chem1211L Final Lab Report BIN XU

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Chemistry

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Feb 20, 2024

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Running head: CHEM 1211 K Final Lab Report 1 Final Lab Report Brianna Tucker April 18th, 2023 Tuesday 11 –2 Unknown Number: P42625-BS-23

II. INTRODUCTION Acids are chemical substances that include hydrogen and are typically liquids that combine with other substances to generate salts. Some acids disintegrate or burn other materials with which they encounter. A base is a chemical that reacts with hydrogen ions to neutralize the acid. Many bases are mineral compounds that combine with acids to create water and salt. Bases include things like oxides, hydroxides, and carbonates of metals. Alkalis are the soluble bases. When the reaction finds the balance, which is frequently demonstrated by a change in shading, titration is the gradual enlargement of one design of known focus referred to as titrant to a known volume of another arrangement of obscure fixation. KHP is a solid, air-stable standard that is used frequently in acid-base titrations because of its mild acidity and ease of accurate weighing. To calculate NaOH's molarity. To find the acidity of weak acids is expressed by the pKa index. III. INDIVIDUAL EXPERIMENTS BY SUBTITLE 3.1. Melting point determinations

inserted a 2-3 mm sample into a capillary tube with a thin wall and a sealed end. then waited for the sample on the glass plate to dry out or turn powdery. To make sure the sample was at the bottom of the tube, I next dropped the tube into a longer tube. After that, insert the tube into the melting pint machine. Finally, when it approached the melting point, the temperature increased quickly before slowing down. 3.3 Determination of equivalent weight First, it was established that organic acid is soluble in a 3:1 solution of ethanol and water. The sample was then dissolved in a mixture of 75% ethanol and 25% water, along with a drop of phenolphthalein, before being titrated with NaOH. then kept an eye on the solution as it dripped until it was fully pink. Finally, after recording the information and calculating the equivalent weight of the unknown using the titration data. 3.4 Computer search KHP was tipped three times. Next, the equivalent weight was computed after the titration was complete. Afterward, she walked over to the computer and searched her lab notebook for the melting point lab. The name of the organic acid was then found by typing in the melting point and the equivalent weight. 3.5 Titration curve and pKa determination

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Initially, I gathered the necessary tools, then I grabbed PH 7 and PH 4. Before beginning the titration, the gadget was then checked to make sure it was reliable and accurate. I gathered all the necessary solutions and combined the organic acid with them. Titration was started after which the PH-measuring instrument was set up. After monitoring for when the PH starts to spark up and reach 12, I finally logged all the changes for every 0.5 to 1.0 added to the mixed solution's flask. IV. RESULTS Melting point determination Standard melting point Standard label melting point Unknown melting point 209-211 209-211 206-207 Determination of equivalent weight Equivalent weight Trial 1 203.144 Trial 2 203.130 Trial 3 185.401 Avg. 195.478 % Dev. 0.001 Titration curve and pKa determination

Solvent system (__mL water and __mL ethanol) % Ethanol PKa in solvent system PKa in water Trial 1 6.25mL water and 18.74mL ethanol 75% 4.00 9.65 Trial 2 8.75mL water and 16.25mL ethanol 65% 3.01 9.65 Trial 3 12.2mL water and 12.5mL ethanol 50% 5.89 9.65 V. DISCUSSION/CONCLUSION Dinitro benzoic Acid is my unidentified acid. Being unable to select data from two options by combining all my data with the last test (a sodium fusion). I had started to draw a conclusion about the unknown, but it was not until it performed the sodium fusion test and recaptured the data that it became clear that the acid did not contain any nitrogen, yet Cl tested positive for being there. Being able to exclude values that were far from the unknown's equivalent weight by first using melting point to limit down her options to those that were closest to my unknown. The later studies confirmed that the melting point predicted was accurate. On all three trials, the pKa experiment did not show a significant jump. As a result, the pKa was far higher than what my sodium fusion and other data indicated. The proper range for the pKa value was between 2.8 and 2.9. The pKa was instead a staggering 4.67. All the information they had previously documented was vastly different from this. Because the equivalent weight and m.p. were so near to the numbers in the research for the unknown acid, this helped to focus my data

and identify it as Dinitro benzoic Acid. From all the information retrieved, the melting point and equivalent weight were a near-exact match, if not by a few points. VI. REFRENCES Chemistry 1211 Lab Manual (The Identification of an Organic Acid) Fifth Edition VII. APPENDIX

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