Pour out the hot water and allow both the thermometer and the beaker to cool. A few additional drops of 95% ethanol were adde d until all the solid dissolved. You can use this information to determine the identity of an unknown through the mixed melting point method. The melting point is the temperature at which the solid coexists in equilibri um with the liquid at atmospheric pressure. She has been teaching Organic Chemistry at the university level for over 15 years and most recently won the 2013 Provost's Award for Excellence in Teaching, Cal Poly Pomona's highest teaching award. Place the beaker on the burner stand and, stirring frequently to insure even heating, carefully heat the water bath with your heat source.
Psst: If you find the content on my website helpful or enjoyable, please buy my favorite and through my Amazon links. There are these really cool things called computers now where all you have to do is press one button and the spelling and grammar of your document are checked. The sample will then be transferred to a Craig tube. To determine the identity of the unknown, the two known compounds with similar melting points will be obtained and be made into mixtures of equal amounts of unknown and known compound. In organic compounds the presence of polarity, or especially hydrogen bonding, generally leads to higher melting point. The melting point of impure acetanilide was 113 ºC and the pure acetanilide melting point was 115 ºC.
The boiling point of a liquid is the temperature at which that liquid is converted to a gaseous state. The first reason was that some of the compound stuck to the glass of the flask when pouring it into a Buchner vacuum funnel. The acetanilide mixture was then filtered via vacuum filtration and a Buchner funnel. Intramuros, Manila Melting Point and Boiling Point of Organic Compounds Group No. On… 1552 Words 7 Pages experimentations, and visually seeing entropy on a graph helps make the concept easier.
The crystals recovered were weighed and the melting point of the impure trans-1,2-dibenzoylethylene and pure trans-1,2-dibenzoylethylene were determined using a Mel-Temp device. Both are low by 1 degree, and given similar melting point depression constants, would have similar levels of impurities. The identity of the unknown liquid was… 1491 Words 6 Pages Organic Chemistry I Lab 5 February 2015 Experiment 1: Utilizing Melting Point and Boiling Point to Determine Unknowns Introduction: One of the first topics learned in most chemistry class is the relation between physical and chemical change. The experiment was composed of two parts: determination of melting points and determination of boiling points. You should now be able to determine the three possibilities for the identity of your unknown. Be sure abbreviations are correct, too: mL, mol, etc.
During the second part of the experiment, the melting point range of pure naphthalene will be measured using a Mel-Temp device. The conclusions drawn from the data found in this lab will aid in the recognition of molecules based on the properties they illustrate. The unknown liquid have colorless and some identical odor characteristics. Experimental Procedure The first part of the experiment is the recrystallization of impure acetanilide. In the two mixtures that contain two different compounds, you should see a drastic change in the melting point since the samples are not pure.
The solution should then be filtered through a fluted filter into a warmed 125 mL Erlenmeyer flask. The accuracy of glassware and balance is to 0. You can determine the melting point of each of the mixtures. The original Erlenmeyer flask was rinsed with hot water to aid in transfering all of the mixture into the fluted filter. This includes repetition both within and between sections of your report.
Decolorizing charcoal will be used to purify the sample. Through the Thomas Hoover apparatus, the melting point of 8 test compounds was determined. With rubber bands, attach the capillary tube to a thermometer and align the bulb of the thermometer with the closed end of the capillary tube. Melting point is one of the characteristics of a chemical compound because it is dependent on the electro negativity and size of the compound. Many factors affect the boiling point and melting point of an organic compound, and one of which is the molecular structure. Materials— The materials used for the experiment include: hotplate, temperature probe, data-collection interface, ring stand, two utility… 2297 Words 10 Pages Introduction: Melting point and Boling point are two fundamental physical properties that are commonly used to identify unknown compounds, to verify already known compounds, and to determine the purity of compounds.
Sources of experimental error include: Densities of liquid vary slightly with temperature. Melting Point of an Organic Compound. You'll simply follow the step-by-step procedure, keeping records of your measurements and observations. During the slow trial, the temperature of the Mel-Temp was raised about 1-2 ºC per minute and the unknown had a melting point of 110. The supernatant was discarded and crystals were taken out of the Craig tube and put onto filter paper using a small spatula.
The indication of purity is, a pure crystal or pure solid is going to have a sharp melting point. The original mixture measured also may not have contained the same amount of each compound, since so little a sample was used … Maybe the original mixture was not mixed well enough, or the ethyl 4-aminobenzoate clung closely to the water molecules. Studying boiling point elevation is a key concept that can only be truly understood through hands on experimentation. As the mixture was filtered, crystals began to form in the filtrate in the 125 mL Erlenmeyer flask. Stronger intermolecular interactions result in higher melting points. For example, if too many decolorizing carbon pellets were added, they would have absorbed some of the acetanilide along with the impurities.