Using Melting Point And Boiling Point At Determining Unknowns

While the other two compounds melted within a couple of seconds. Vapor might have formed on the sides of the test tube for unknown 1 because of the reason that the distilled water within the compound began to evaporate. If the distance between the flame and the test tube differed, the test might have gone wrong, yielding in incorrect results. Because of the strength of ionic compounds, it takes more energy to break their bonds. With the rise of heat, comes the rise of energy, which is the reason why ionic compounds have high melting points as well as high boiling points. The melting point of sodium chloride is 801°C and copper chloride is 498°C. The melting point of citric acid is 153°C and sucrose is

Melting points are indicative of identifying an unknown product and the level of impurity the product contains. In this case, the possible identity of the product based on its melting points are determined by comparing the obtained melting points of the product to the melting points of the five possible products. Two mini capillaries, containing the product only, were used to determine the product’s melting point. For one mini capillary, the temperature range was 132.1-134.2℃, and the product’s melting point for the second minicapillary ranged from 135.1-137.5℃. In addition, melting points were obtained with the product mixed with meso-hydrobenzoin. The temperature range was 135.0-136.0℃ and 135.0-137.5℃. Although the recorded melting point values fall into the racemic range, but the results still indicate that the product is a meso-hydrobenzoin. The melting point values for the product mixed with the meso-hydrobenzoin standard explains that it is unlikely that the product is racemic. The melting point values were two degrees from each other due to the meso-hydrobenzoin standard making

The purpose of this experiment is to identify an unknown substance by measuring the density and boiling point. I will be able to conclude which substance is my own from a list of known options stating what its real boiling point and density is.

In determining the melting point range of the aspirin, a capillary tube (sealed at one end) was one-third-filled with the dried aspirin. The capillary tube and a thermometer were immersed in an oil bath. The temperature at which the solid started to melt and the temperature when the entire sample was completely liquefied were recorded as the melting point temperature range.

In the first part of the experiment trans-cinnamic acid began to melt rapidly at 133 °C and had completely liquefied at 135.9 °C. Urea began to melt rapidly at 133 °C, just as the trans-cinnamic acid, but had completely liquefied at 134.7 °C. Both urea and trans-cinnamic acid had true melting points of 132 °C generating a .75 percent error. The 50:50 mixture of urea and trans-cinnamic acid started to melt quickly at 98.5 °C, slowed down at 102 °C, at which point most of the compound had seemed to have melted with the exception of a few crystals, which did not melt completely until 125°C . In the second part of the experiment, the melting point of an unknown compound was measured at a fast rate, 10 °C/min, in order to obtain an estimate of the melting point of that compound, which was about 130 °C – 139 °C. At this point the suspected organic compound was benzoin, and the melting points of the two compounds, benzoin and the unknown, as well as the 50:50 mixture of each, were obtained. The unknown compound, along with the benzoin, had identical melting points of 133.7°C – 134.9°C, while the 50:50 mixture had a melting point of 133 °C – 134.3 °C. The true melting point for benzoin is 132°C, generating a .75 percent error.

I. LIQUID - Identification of an Unknown Liquid: Using the physical properties of Solubility, Density, and Boiling Point.

Lowe, B. (n.d.). ["Experimental Cookery From The Chemical And Physical Standpoint Read more: http://chestofbooks.com/food/science/Experimental-Cookery/The-Boiling-Point-Of-Water-And-Solutions.html#ixzz4Lyhecg47]. Retrieved October 02, 2016, from

After each of the solids were completely dry, each was placed into a MelTemp device. The temperature at which each solid began to melt and completed melting was recorded.

The purpose of this lab was to study colligative properties. These properties are properties that are affected when a solute is added to a solvent. Thus, the amount is important, not the actual type of substance, for the colligative properties. A couple types of this property are the freezing point and boiling point of a substance. (1)

Chemical changes are often accompanied by physical changes. Three that you should not see in this lab are changes in temperature, presence of a flame, and evolution of light, as when as firefly glows. Three physical changes that indicate a chemical change may have occurred (and that may be seen in this lab) are:

In this experiment, the identity of an unknown compound will be deduced from analysis of physical properties, boiling points, IR spectra, chemical tests, and melting points of derivatives. This experiment allows for individual selection of chemical tests, order of steps, and additional analysis, as necessary, based on what is needed to determine identity of unknown.

In the chemical and physical change lab, we figured out what a chemical change is. A chemical change is a change in which one or more substances are converted into a different substances. That means if a chemical change occurred the substances will be turned into a different substance. In order to know if a chemical change happened you will see bubbles, a color change, energy released as heat and light or a solid participate. The first example, of a chemical change in this lab is bubbles. In stations 6 and 8 each had bubbles in them. In station 6 the zinc was put into the HCI acid and once they touched they got bubbly and cloudy. Also in station 8 when a spoonful of baking soda and HCI acid touches the solution, it started to bubble and fizz.

The objectives of this lab are, as follows; to understand what occurs at the molecular level when a substance melts; to understand the primary purpose of melting point data; to demonstrate the technique for obtaining the melting point of an organic substance; and to explain the effect of impurities on the melting point of a substance. Through the experimentation of three substances, tetracosane, 1-tetradecanol and a mixture of the two, observations can be made in reference to melting point concerning polarity, molecular weight and purity of the substance. When comparing the two substances, it is evident that heavy molecule weight of tetracosane allowed

Melting range would be closely related to a mixed sample whose constituents are most identical. In other words, melting point will have a wide range and would be below 200°C and above 95°C.

Brittain, C. G. (2009). Using Melting Point to Determine Purity of Crystalline Solids. Retrieved from http://www.chm.uri.edu/mmcgregor/chm228/use_of_melting_point_apparatus.pdf