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Chem 123 Experiment 1

Chem 123 Experiment 1 - Introduction Alkenes are basically...

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Introduction Alkenes are basically hydrocarbons that have a C=C double bond within their structure, with the double bond itself being both stronger and more reactive than its single counterpart. Hydrocarbons with double bonds also used to be called "olefins", because they had an oily appearance. Isomers (or in this case geometric isomers) are basically compounds that have the same formula, but have different structure, hence giving then different properties. For most types of alkenes, there are two different types of geometric isomers. This is caused by the double bond found their structure, which limits their ability to twist and take different shapes. The two types of isomers are called cis and trans. Cis isomers tend to have their main molecular group on the same side of the molecule, while trans isomers have their important molecular groups will be on opposite sides/corners of the molecule (Hovde, 2008). Overall, trans tends to be more stable than cis , and this is due to their heat of formation. Heats of formation, denoted as ΔH o f , are the change in heat for some system when a molecule is formed. If they are negative, it means that heat is released, meaning the reaction is exothermic. The delta heats of formation for trans compared to cis is roughly 1 kcal/mol, and that slight difference in values makes of trans makes it more stable in structure. A steric hindrance is when a group of molecule/atoms get too close to each other, resulting in a repulsion effect between the effected electron clouds. The point of this is to investigate the interaction between the cis and trans isomers of 1, 2- ethylenedicarboxylic acid. The cis isomer is also known as "maleic acid" and the trans isomer is also known as "fumaric acid". This will be done by filtering the maleic anhydride in two steps:
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first by mix the powder with water and filtering the solution and second, mixing the supernatant from the first reaction with HCl, in order to obtain 2 different white powders. Then, by testing their solubility and melting points, the substances will be identified as either maleic acid or fumaric acid. Experimental Method and Materials The experiment procedure used for this experiment was outlined in the CHEM 123L lab manual, under experiment #1. All steps were followed with no deviation in procedure. (Stathopulos,2009) Experimental Observations Mass : Powder 1: 5.57 g Powder 2: 2.34 g Theoretical Temperatures: Maleic Acid: 139°C - 140°C (Chemical Safety Information from Intergovernmental Organizations, 1997) Fumaric Acid: 300°C -302°C (Chemical Safety Information from Intergovernmental Organizations, 1995).
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