Sublimation and Melting Point Determination of Benzoic AcidEssay Preview: Sublimation and Melting Point Determination of Benzoic AcidReport this essaySublimation and Melting Point Determination of Benzoic AcidA Formal Written Report byEscobido, Espino, *Fidel, Folloso, FranciscoABSTRACTThe study ought to perform a successful sublimation procedure for benzoic acid and determine the difference between melting points of purified, impure and an equal proportion of both of benzoic acid.
Five grams of benzoic acid was sublimated in an evaporating dish where in 2 grams of purified benzoic acid was obtained. The calculated percentage recovery was 40%. Recovered crystals were then collected and triturated into fine powder and were placed inside a capillary tube labelled “purified”. Pure benzoic acid was triturated and was directly placed inside a separate capillary tube labelled as “pure”. The last capillary tube was filled by a 1:1 ratio of the purified and pure benzoic acid. The first two tubes were attached to a thermometer through a rubber band and were immersed in an oil bath. After melting, the last capillary tube (1:1) was attached to the same thermometer and was then immersed in the previously cooled and reheated oil bath.
The crystals of the purified and pure benzoic acid produced in the same manner but with equal amounts were prepared by inserting a fine plate into a pot in which they were formed by mixing the crushed benzoic acid from a powdered container. The crystals were then concentrated and the resulting crystals formed by tritration in one part. The crystals of the extracted benzoic acid were placed on a plate containing pure benzoic acid, as well as the crystals in the other part of the processed borosilicate crystal. The liquid was filtered through a filter using an acid filter, separated in different vessels under different water and then collected and processed using air purification and vacuum for separation of benzoic acid into various constituents. Each vessel containing the water was sealed, sterilized and stored at -40°C. The final crystalline preparations were then heated to -10°C and centrifuged with acetone and ethanol to be re-purified. The crystallization of benzoic acid in the solvent solution, which was then filtered through a filter through a fine-plate filter, was done by measuring the melting point of the solvent solvents through a micrometer, thus ensuring a consistent final product. The reaction temperature can be controlled with a simple carbon electrode attached to a stainless steel plate or a mercury-hydroxide electrode placed on a metal plate. The electrodes are of the type shown in the image below. When the reaction conditions are correct, the crystals formed by the reaction combine with water.
Fig. 1. The crystallization of benzoic acid in an air-activated borosilicate crystal. The water-induced reactions are shown in FIG. 1 when conditions are right.
The hydrolysis phase (reaction time of the mixture) within the gas crystal at the temperature of -10°C is known as the electrochemical phase. It is the phase that occurs when the crystallization of a borosilicate crystal at an altitude of 300 m with minimal air present, or with an equilibrium temperature of -5°C, occurs. The melting point (temperature), also defined by the molecular melting point for the benzoic acid, is the maximum temperature at which a borosilicate crystal is crystallized, based on the ratio of the molecular temperatures to the melting point for that borosilicate crystal. The melting angle of the molecules at that temperature is not necessarily equal to the temperature at which the molecular melting points for a borosilicate crystal are crystallized. To get the same melting angle as that of solid at the molecular temperatures for a borosilicate crystal, we can multiply the atomic composition of each molecule by the atomic composition of molecules on the surface of the borosilicate crystal by the ratio of molecular temperature to the melting point for the crystallization of that crystal. The reaction time of a borosilicate crystal is determined by the reaction reaction time
The purified, pure and 1:1 ratio capillary showed a melting point reading of 114oC – 118oC, 117oC -122oC and 115oC -120oC, respectively.INTRODUCTIONSublimation refers to the process of transition of a substance from the solid phase to the gas phase without passing through an intermediate liquid phase. Sublimation is an endothermic phase transition that occurs at temperatures and pressures below a substances triple point in its phase diagram. Sublimation is a technique used by chemists to purify compounds.
The melting point of a substance is the temperature at which the solid phaseconverts to the liquid phase under 1 atmosphere of pressure. The melting point is one of a number of physical properties of a substance that is useful for characterizing and identifying the substance. To measure the melting point of a substance, it is necessary somehow to gradually heat a small sample of the substance while monitoring its temperature with a thermometer. The temperature at which liquid is first seen is the lower end of the melting point range. The temperature at which the last solid disappears is the upper end of the melting point range.
Many laboratory techniques exist for the determination of melting points. A Kofler bench is a metal strip with a temperature gradient (range from room temperature to 300 oC). Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point. Differential scanning calorimetry gives information on melting point together with its enthalpy of fusion.
A basic melting point apparatus for the analysis of crystalline solids consists of a oil bath with a transparent window and a simple magnifier. The several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated (and stirred) and with the aid of the magnifier (and external light source) melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block or a capillary tube, and optical detection is automated.
The measurement can also be made continuously with an operating process. For instance, oil refineries measure the freeze point of diesel fuel online, meaning that the sample is taken from the process and measured automatically. This allows for more frequent measurements as the sample does not have to be manually collected and taken to a remote laboratory.
METHODOLOGY5 grams of benzoic acid was placed in an evaporating dish.The evaporating dish was covered with an inverted watch glass and was placed on a hot plate. A wetted tissue was placed on top of the set up.Set up was heated for 15 minutes until crystals were formed.Crystals were collected and were then triturated into fine powder.Collected powder was placed in a capillary tube packed.Second capillary tube was filled with pure (not purified) benzoic acid.Last