The substitution reaction was successful but not fully effective. 19. If the data was inconclusive, then comparing various compounds and the unknown based on physical characteristics would be the first step, titrations would also be a good method. 20. To get a better yield, redoing the experiment would require careful attention in the recrystallization steps: amount of solvent used, how hot solvent is, if the mixture cools to room temperature before placing it in an ice
Purpose/Introduction The process of recrystallization is an important method of purifying a solid organic substance using a hot solution as a solvent. This method will allow the separation of impurities. We will analyze Benzoic Acid as it is dissolved and recrystallized in water and in a solvent of Methanol and water. Reaction/Summary In Experiment One we will be recrystallizing Benzoic Acid from water. In Experiment Two we will be recrystallizing Benzoic Acid using a solvent pair made up of Methanol and Water.
Experimental Procedure A dry, empty freezing-point tube and its cork were weighed together. Carefully, 15-20g of pre-cooled cyclohexane was poured into the freezing-point tube, the tube recorked, and the whole thing was reweighed, to find the exact mass of the cyclohexane. The dry thermistor and stirrer were inserted into the FP tube, ensuring they were immersed in the liquid. A large beaker was filled with ice and water, which the FP tube was placed into. The cooling curve was determined by recording the temperature at regular time intervals (every fifteen seconds) as the cyclohexane cooled, until the temperature became constant.
Summary Determining the concentration of a liquid can be a tricky process involving complex procedures if it were not for science’s ability to test a substance’s absorbency through spectrophotometry. The experiment was carried out to discover the concentration of Red Dye #40 in several common soft drinks. The samples of the dye were diluted, and tested using a spectrophotometer. The absorbencies of these samples were then recorded, and a standard line curve with the concentration equation and R2 value was created with these results. Using the absorbencies of the dye samples, the concentrations of the soda samples were determined using the slope equation provided by the graphing software.
When we tested methanol, triphenylmethan did not dissolve at room temperature, but did dissove when the methanol was hot, and then recrystalized into a solid when the mehtanol was cooled, so this was a suitable solvent. When we tested toluene, triphenylmethan dissolved right away at room temperature and was therefore determined to be not suitable for recrystalization. Had we been required to find a solvent for trimyristin, we would have undergone the same tests with various potential solvents for it. Extraction is the transfer of a solute from one phase to another. Adding a solvent to a solid that only dissolves certain compounds in the
The molar mass of a volatile liquid can be obtained by measuring the temperature, pressure, mass, and volume in a gaseous state. The equation used to determine the molar mass is derived from the Ideal Gas Law equation. The objective of this experiment aims to determine the molecular mass of a
Dissolution is the process that makes solutions. A solution is a homogenous mixture of two or more substances. The solute in the solution is the substance that is dissolved, while the solvent in the solution is the substance that dissolves the solute during dissolution. The question introduced in this lab is “What factors influence the rate at which one substances dissolves in another?” The three factors that affect the rate of dissolution are temperature, how much you stir the mixture, and the particle size of the substances. Temperature increases the chance of solute and solvent particles colliding with one another.
They tested how the temperature would affect the rate of reaction. This was observed by the amount of time it took for the solution to change colors. For many chemical reactions there is an optimum temperature at which the chemicals will react with each other. As was found in their experiment, the temperature affected the rate of reaction. (Deoudes, 2010).
Purpose The purpose of the experiment was to determine the molar mass of unknown solute number 1. This was done by using colligative properties of solutions specifically, freezing point depression. Colligative properties depend on the number of molecules that are present in the solution rather than the nature of the molecules . This fact is useful because knowing this allows one to use the properties of the number of molecule in the solution without needing to worry too much about the nature of the molecules. Using this knowledge, the experiment consisted of freezing cyclohexane over 4 trials, 3 trials involved increasing amount of salt while the first was pure cyclohexane.
What supports this possibility was the fact the product was unable to be 100% dried. This resulted in a material that was more like slightly wet clay then a solid crystal and possibly contain petroleum ether which would result in a lower melting point. Another possible reason was the final product was not, in fact, triphenylmethanol, un pure or