Melting pointe determination #01 Introduction: Objective To learn how to obtain an accurate melting point using a MELTING POINT APPARATUS‚ then use them to draw eutectic curve and determine the eutectic point. Melting point of a solid is the temperature at which the solid and its liquid form are in equilibrium‚ i.e.‚ molecules move back and forth between the two states at the same rate‚ so both phases remain present. If the temperature of a solid is measured carefully as the solid is heated
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BENZOIC ACID & BENZOATES (210 –218) • Retards growth of bacteria and yeasts • Occurs naturally in many foods – a similar distribution to salicylate (but at a lower dose than as an additive) • Common food sources: Soft drink‚ cordial‚ fruit juice and cider Liquid essences and syrups Iceblocks‚ jelly‚ low joule jam‚ dips‚ pickles‚ olives Fish marinades and preserves • PABA (para-amino-benzoic-acid)
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A carboxylic acid is an organic acid characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH‚ where R is some monovalent functional group. A carboxyl group (or carboxy) is a functional group consisting of a carbonyl (RR’C=O) and a hydroxyl (R-O-H)‚ which has the formula -C(=O)OH‚ usually written as -COOH or -CO2H. Carboxylic acids are Brønsted-Lowry acids because they are proton (H+) donors. They are the most common type of organic acid. Among
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structures and properties of amino acids know the groups of amino acid What are amino acids? Amino acids are molecules that when combined with each other proteins. Amino acids contain a central tetrahedral carbon atom (α-carbon) amine group‚ carboxyl group‚ R-side chain The R-side chain determines the different amino acids There are 20 common amino acids Amino acids can join via peptide bonds Several amino acids occur only rarely in proteins Some amino acids are not found in proteins 3D
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Cause and Effect on Acid Rain Introduction Beautifully crafted statues are now worn out or severely damaged‚ aquatic wildlife population are dying off‚ forests have lost the leaves that protect their trees and produce food‚ and the rates of lung diseases in humans are rising around the world. The cause of all of these problems can be linked back to acid rain. Most people don’t understand the concept or science behind acid rain. The common belief is that it’s a natural process‚ but it’s actually
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The intent of this paper is to educate individuals about acid rain‚ define its chemical makeup‚ and describe its impact on the environment. Rain is an important part of all life; it is the source of water for almost everything. In some areas rain is actually a threat to life because of pollution from cars‚ factories‚ and power plants. This pollution releases gases into the atmosphere to create acid rain. Acid rain is rain‚ or any other form of precipitation that is uncharacteristically acidic
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and these comprise only 20 kinds of amino acids in various combinations. These 20 kinds of amino acids are essential to the body. In addition to being the materials for proteins‚ they are used as an energy source for the body as necessary. Further‚ each amino acid plays an important and unique role in the body. The list below shows the role of each amino acid. | Valine Leucine Isoleucine | All of these 3 amino acids are called branched chain amino acid(BCAAs). They perform the important functions
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Citric Acid Names of chemical substance- Chemical formula: C6H8O7. Elements present in citric acid are; carbon‚ hydrogen and oxygen. Bonding- All the elements in citric acid are non-metals. Citric acid has a covalent bond type. History- in the 8th century jabir ibn hayyar a Persian alchemist was credited with the discovery of citric acid. in 1784 the separation of citric acid from citrus fruits occurred when Swedish chemist Carl Wilhelm Scheele separated citric acid from lemon juice. The next
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Science one world essay – Acid Rain Acid rain has been an important global issue for centuries. Although most acid rain is caused by human activities‚ some acid rain occurs naturally. An example of natural acid rain is erupting volcanos‚ they give off smoke containing water vapor‚ carbon dioxide‚ sulphur dioxide and nitrogen compounds. The sulphur dioxide and nitrogen compounds cause small amounts of acid rain near the volcano. Pure water is not an acid‚ but even clean rainwater is slightly acidic
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Recrystallization of Benzoic Acid Objective To purify benzoic acid by recrystallization and gain experience with a basic organic laboratory techniques. Background Products of chemical reactions are often contaminated with impurities. One method for purifying chemicals‚ recrystallization‚ takes advantage of the differences in the solubilities of the desired products and the impurities and the tendency for the slow formation of crystals to exclude impurities from the crystalline solid. HC HC
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