[Pharmaceutical Chemistry] Melting Point and Boiling Point Essay Example

ones. The objective was achieved seeing as the melting and boiling point of the samples were obtained, however, there were deviations from the theoretically obtained ones which could be attributed to factors like human error (inaccuracies), impurity of the sample and laboratory condition.

INTRODUCTION: Melting point, by definition is the range of temperature at which a substance changes from solid to liquid state, while boiling point refers to the temperature at ores that hold them in the liquid state. These properties are greatly affected by intermolecular forces of attraction which could be held responsible for how compounds will react to external forces like pressure or temperature.

The size and structure orientation of the molecules are also a huge factor in the melting point and boiling point because the more complex the structure, and the smaller the structure, the harder it is to break the bonds between molecules.

The purity of the sample is also another factor because theoretically speaking, when a sample is contaminated, its melting and boiling point would be efferent from the pure ones, thus causing inaccuracies in the values obtained. Malice Acid is a solid, white crystalline granular powder which has a strong acidic taste, is combustible and is slightly hygroscopic. Its molecular weight is 134. 1 g/mol, and it is soluble in water and alcohol, slightly soluble in ether and insoluble in benzene.

The molecule forms a Hydrogen bond with other molecules. It is bound by a strong force that keeps the molecules in the solid state at room temperature.

The temperature range needed to reach to be able to break down this force is the melting point. The theoretical melting

point of this compound is 130;C. Figure 1. Structure of Malice Acid Retrieved from: http://chemistry.

About. Com/do/facetiousness/gig/chemical- Structures---M/Malice-Acid. HTML Ethyl acetate is a clear-colored liquid which has a sweet smell. It is an industrial acid and is slightly immiscible with water, but miscible in ethanol, acetone, ethyl ether and benzene. Its molecular weight is 88.

1 g/mol, and it is flammable. It forms a dipole-dipole attraction between molecules.

This force is less strong than the H- bonding like malice acid but strong enough for it to be in the liquid state at room imperative. The temperature needed to overcome this force is the boiling point.

Figure 2. Chemical Structure of Ethyl Acetate Retrieved from: http://detoxified. Org/display/detoxified/Ethyl+Acetate The experiment is achievable in a three-hour time frame seeing as the materials are readily available in a laboratory, however the limited Mel-temp (apparatus) available during the time the experiment was conducted proved to be a barrier to the time efficiency seeing as several groups had to take turns borrowing it.

MATERIALS AND METHODS: We were asked to determine the melting point and boiling point of two reagents, Akers (250 ml) for the water bath and oil bath, a thermometer, rubber bands, three capillary tubes, a bullet (ml test tube), a paper clip or safety pin, wire gauze, forceps, a simple distillation apparatus which includes a distilling flask, iron stands, iron clamps, rubber tubing, a Liable condenser, a receiving flask and cork stopper to properly seal the set-up. Cooking oil and water were used as the liquids for the hot baths.

The Melting Point Determination of Malice Acid The melting point of malice acid was first determined using the

rough method which is a prerequisite in identifying the exact melting point of the sample. A one end sealed capillary tube was used to contain the sample with dimensions of 1 mm in diameter and 5 CM in length. Using the paper clip or safety pin, the malice acid powder was inserted 1 CM inside the tube. The prepared capillary tube was then attached to a thermometer using a rubber band or rubber ring. The prepared set-up was immersed in the oil bath. With the use of a stove, the temperature of the oil bath increased.

The temperature range recorded was from when the substance began to liquefy until it has completely melted. Figure 3. Melting Point Determination Setup (Rough Method) Retrieved from: Paraphernalia Experiment 1: Melting Points and Boiling Points In the next set-up in which the melting point of the substance is determined using the accurate method, the Mel-temp apparatus was used. Another capillary tube with malice acid and one end sealed is prepared and inserted inside the Mel-temp. The temperature was increased slowly at a rate of 1-2 degrees per minute.

When the capillary tube is already clear, the temperature was recorded.

The Boiling Point Method Determination of Ethyl Acetate In the determination of the boiling point of ethyl acetate using the rough method, a et-up for simple distillation was prepared. 50 ml of ethyl acetate was placed inside the distilling flask after rinsing it with the sample. The thermometer was attached with the cork stopper. The Liable condenser was connected with the distilling flask using a cork stopper to properly seal it.

A receiving flask was prepared at the end of

the condenser. Water was placed inside the condenser and the sample was heated. At the first few drops (that will reserve ml) of the distillate, it was disposed.

The range of temperature recorded was when the first drop of the distillate arrives at the achieving flask until the temperature of the sample becomes constant after continuously heating.

Figure 5. Boiling Point Determination Setup (Accurate Method) Retrieved from: The distillate was used for the last part of the experiment which involves the determination of the boiling point of ethyl acetate using the accurate method. A capillary tube with one sealed end is placed inside a bullet, with the sealed side on top. The distillate or ethyl acetate was placed inside the bullet until it reached the top of the capillary tube.

It was then attached to a thermometer using a rubber band.

The set-up was then submerged in a water bath. The temperature was increased slowly using a stove until the capillary tube emitted a continuous and rapid stream of bubbles. Then, the heat was removed. The range of temperature was recorded from when the capillary tube stopped giving out bubbles until the ethyl acetate went inside the capillary tube. RESULTS AND DISCUSSION: Sample Method Theoretical Melting Point Experimental Melting Point Malice Acid Rough 127-133;c 130-136;c Accurate 142;c Table 1.

Determination of the Melting Point of Malice Acid In the determination of the melting point of malice acid, the data in table 1 has been obtained. Using the rough method, the initial temperature has been obtained when the malice acid started to melt or liquefy, which was 130;C. The final temperature was recorded when the malice

acid completely melted which was 136;C. By definition, the melting point of a substance is a range. Thus, using the rough method, malice acid has melting point of 130-136;C. In the accurate method, the Mel- temp@ was used.

By the time the capillary tube became clear, a temperature of 142 ;C was recorded. Comparing the experimental results to the theoretical results, the data showed close values with a 6. 34% error in the accurate method and overlapping results in the rough method. The inaccuracy of the actual result as slightly hygroscopic and is reactive with oxygen.

Once a container of laboratory synthesized malice acid had been opened, it starts oxidation which then forms Exaltation Acid. Sample Theoretical Boiling Point Experimental Boiling Point Ethyl Acetate 77. 1 ;c 69-76;c 68-71 ;c Table 2.

Determination of the Boiling Point of Ethyl Acetate The data in Table 2 shows the theoretical and experimental boiling points of ethyl acetate.

In the rough method, the temperature 69;C, was recorded when the distillate first dropped in the receiving lass. The final temperature, 76;C, was obtained when the temperature remained constant while continuously heating the ethyl acetate. It committed a percentage error of 1. 43% from the theoretical boiling point. In the accurate method, an initial temperature of 68 ;C was recorded when the continuous stream of bubbles stopped coming out of the capillary tube with a percentage error of 7.

1%. The data gathered from the experiment was relatively close to the theoretical data although with minor discrepancies. These errors may be attributed mostly to human error. Such are inaccurate reading and measurement, exposure of the substance to contamination or impurities,

or a delayed reaction time in recording the data. It also shows how the rough method and accurate method differs from each other.

Ideally, the accurate method would show a closer value to the theoretical values because from definition, accuracy is the correctness or exactness of a measurement to a fixed and absolute value.