The goal of the project was to characterize an "unknown" organic acid in order to make a proper identification of the acid, while learning proper techniques for scientific measurement and analysis of error.
In order to ensure the most accurate data, a purification was performed by the process of recrystallization. To perform the recrystallization the powder was dissolved in a minimal amount of hot ethanol/H2O solvent that allowed the unknown powder to crystallize properly when cooled. This process allowed for the removal of soluble impurities when suction filtered. A sample of the unknown acid was weighed at 8.24 g, and it was found that 164ml of a 40% ethanol, 60% H20 solvent dissolved the 8.24 g of unknown acid when heated. The
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Phenolphthalein was used as an endpoint indicator to determine the molarity of the NaOH solution, which was found to be approximately .0979 M. The data collected from the titration follows in the table below.
"NaOH Titration"
Trial I II III
Mass KHP (g) .403 .402 .411
Final NaOH 21.02mL 41.04mL 30.01mL
Initial NaOH .89mL 21.02mL 9.50mL
Volume NaOH Total 20.13mL 20.02mL 20.60mL
Molarity NaOH .0980 M .0980 M .0977 M
The molarity of each trial was found using the formula below; following the formula is a sample calculation:
Molarity of NaOH Solution = Mass KHP (g) / [(204.34 g/mole) x (Delivered NaOH (ml)]
.403g /[(204.24g/mole)x(0.02013L)] = .0980 moles/liter
To ensure the best possible data, the error of the collected data was determined. This error was found to be: (9.80-9.77)/9.77 = .003 x 100% = .31% error.
The equivalent weight of the unknown was determined by titration with NaOH. By discovering the amount of NaOH required to react with the unknown acid, it was possible to determine the equivalent weight of 98.4 g/mole. Three samples of the pure unknown acid were weighed at .403g, .406g, and .394g. Each sample was placed in a flask and dissolved in approximately 40-50mL of the heated solvent used in the recrystallization (40% ethanol/60% H2O). A drop of Phenolphthalein was added to each flask. Each flask was titrated with the standardized
(.1063 KIO31) (1 mol KIO214 g) x 6 mol S2O41 mol KIO= .00298.04150= .259 M
The purpose of this semester long experiment was to determine an unknown organic acid. An organic acid is an organic compound with acidic properties. A base reacts with acids to form salts. Titrations are used to determine the concentration of unknown substances. The purpose of the KHP experiment was to determine the molarity of NaOH. HCl titrations are mainly to check technique and used to verify the molarity of NaOH solution. The hypothesis is that this acid is C4H3OCOOH.
We know that that the end point of the titration is reached when, after drop after careful drop of NaOH, the solution in the flask retains its pale pink color while swirling for about 30
In this experiment, an unknown Grignard reagent was prepared from an aryl halide. The unknown reagent was then reacted with carbon dioxide to form a carboxylic acid. The solid acid was then isolated and recrystallized before the melting point was taken. The precipitate was then dissolved in water and titrated to determine the molecular weight. The melting point and molecular weight were then used to determine the unknown acid obtained from the experiment.
The purpose of this experiment was to determine the pKa, Ka, and molar mass of an unknown acid (#14). The pKa was found to be 3.88, the Ka was found to be 1.318 x 10 -4, and the molar mass was found to be 171.9 g/mol.
The problem that was trying to be solved in this study deals with analyzing unknown solutions. In this particular case, a chemical company has several unknown solutions and to correctly dispose of them they need to know their properties. To figure out the properties several qualitative tests were performed throughout the study (Cooper 2012).
Purpose: The purpose of this experiment is to observe chemical changes in common consumer products to determine if the chemicals are basic, acidic, or remain neutral when mixed with other chemicals.
This experiment combined all the knowledge of the previous labs performed throughout the semester. An unknown mixture containing an organic acid or base and an organic neutral compound in nearly equal amounts needs to be separated to its separate components. An understanding of solubility, extraction, crystallization and vacuum filtration is necessary in order to
Identifying this organic acid was an extensive task that involved several different experiments. Firstly, the melting point had to be determined. Since melting point can be determined to an almost exact degree, finding a close melting point of the specific unknown can accurately point to the identification of the acid. In this case the best melting point
One milliliter of 6.00-M phosphoric acid was placed into a 125-mL Erlenmeyer flask using a volumetric pipette. Using a slightly larger pipette, six milliliters of 3.00-M sodium hydroxide was transferred into a 50-mL beaker. Then a disposable pipette was used to slowly mix the sodium hydroxide into the phosphoric acid while the solution was swirled around. Then both the beaker and flask were rinsed with 2-mL of deionized water and set aside. A clean and dry evaporating dish was weighed with watch glass on a scale. Then the solution was poured into the dish and the watch glass was placed on top. The solution was then heated with a Bunsen burner to allow for the water to boil off to reveal a dry white solid. After the dish cooled to room temperature it was once again weighed and the new mass was recorded.
By using acid-base titration, we determined the suitability of phenolphthalein and methyl red as acid base indicators. We found that the equivalence point of the titration of hydrochloric acid with sodium hydroxide was not within the ph range of phenolphthalein's color range. The titration of acetic acid with sodium hydroxide resulted in an equivalence point out of the range of methyl red. And the titration of ammonia with hydrochloric acid had an equivalence point that was also out of the range of phenolphthalein.. The methyl red indicator and the phenolphthalein indicator were unsuitable because their pH ranges for their color changes did not cover the equivalence points of the trials in which they were used. However, the
In this experiment, 0.31 g (2.87 mmol) of 2-methylphenol was suspended in a 10 mL Erlenmeyer flask along with 1 mL of water and a stir bar. The flask was clamped onto a hotplate/stirrer and turned on so that the stir bar would turn freely. Based on the amount of 2-methylphenol, 0.957 mL (0.00287 mmol) NaOH was calculated and collected in a syringe. The NaOH was then added to the 2-methylphenol solution and allowed to mix completely. In another 10 mL Erlenmeyer flask, 0.34 g (2.92 mmol) of sodium chloroacetate was calculated based on the amount of 2-methylphenol and placed into the flask along with 1 mL of water. The sodium chloroacetate solution was mixed until dissolved. The sodium chloroacetate solution was poured into the 2-methylphenol and NaOH solution after it was fully dissolved using a microscale funnel.
5. In reaction three, the number of moles of NaOH can be calculated from the concentration of the solution (1.0M = 1.0mole/L) and the volume used. The calculation is below. Enter the result into Data Table 2.
1. To titrate a hydrochloric acid solution of “unknown” concentration with standardized 0.5M sodium hydroxide.
Objective: The objective of this experiment is to use acid-base extraction techniques to separate a mixture of organic compounds based on acidity and/or basicity. After the three compounds are separated we will recover them into their salt forms and then purify them by recrystallization and identify them by their melting points.