What Causes Hydrogen Bonding

Hydrogen bonding occurs between a hydrogen atom and an electronegative atom (e.g., oxygen, fluorine, chlorine). The bond is weaker than an ionic bond or a covalent bond, but stronger than van der Waals forces  (5 to 30 kJ/mol). A hydrogen bond is classified as a type of weak chemical bond. Why Hydrogen Bonds Form The reason hydrogen bonding occurs is because the electron is not shared evenly between a hydrogen atom and a negatively charged atom. Hydrogen in a bond still only has one electron, while it takes two electrons for a stable electron pair. The result is that the hydrogen atom carries a weak positive charge, so it remains attracted to atoms that still carry a negative charge. For this reason, hydrogen bonding does not occur in molecules with nonpolar covalent bonds. Any compound with polar covalent bonds has the potential to form hydrogen bonds. Examples of Hydrogen Bonds Hydrogen bonds can form within a molecule or between atoms in different molecules. Although an organic molecule is not required for hydrogen bonding, the phenomenon is extremely important in biological systems. Examples of hydrogen bonding include: between two water moleculesholding two strands of DNA together to form a  double helixstrengthening polymers (e.g., repeating unit that helps crystallize nylon)forming secondary structures in proteins, such as alpha helix and beta pleated sheetbetween fibers in fabric, which can result in wrinkle formationbetween an antigen and an antibodybetween an enzyme and a substratebinding of transcription factors to DNA Hydrogen Bonding and Water Hydrogen bonds account for some important qualities of water. Even though a hydrogen bond is only 5% as strong as a covalent bond, its enough to stabilize water molecules. Hydrogen bonding causes water to remain liquid over a wide temperature range.Because it takes extra energy to break hydrogen bonds, water has an unusually high heat of vaporization. Water has a much higher boiling point than other hydrides. There are many important consequences of the effects of hydrogen bonding between water molecules: Hydrogen bonding makes ice less dense than liquid water, so ice floats on water.The effect of hydrogen bonding on heat of vaporization helps make perspiration an effective means of lowering temperature for animals.The effect on heat capacity means water protects against extreme temperature shifts near large bodies of water or humid environments. Water helps regulate temperature on a global scale. Strength of Hydrogen Bonds Hydrogen bonding is most significant between hydrogen and highly electronegative atoms. The length of the chemical bond depends upon its strength, pressure, and temperature. The bond angle depends on the specific chemical species involved in the bond. The strength of hydrogen bonds ranges from very weak (1–2 kJ mol−1) to very strong (161.5 kJ mol−1).  Some example enthalpies in ​vapor are: F−H†¦:F (161.5 kJ/mol or 38.6 kcal/mol)O−H†¦:N  (29 kJ/mol or 6.9 kcal/mol)O−H†¦:O (21 kJ/mol or 5.0 kcal/mol)N−H†¦:N (13 kJ/mol or 3.1 kcal/mol)N−H†¦:O (8 kJ/mol or 1.9 kcal/mol)HO−H†¦:OH3  (18 kJ/mol or 4.3 kcal/mol) References Larson, J. W.; McMahon, T. B. (1984). Gas-phase bihalide and pseudobihalide ions. An ion cyclotron resonance determination of hydrogen bond energies in XHY- species (X, Y F, Cl, Br, CN). Inorganic Chemistry 23 (14): 2029–2033. Emsley, J. (1980). Very Strong Hydrogen Bonds. Chemical Society Reviews 9 (1): 91–124.Omer Markovitch and Noam Agmon (2007). Structure and energetics of the hydronium hydration shells. J. Phys. Chem. A 111 (12): 2253–2256.

My Statement of Purpose Engineering Management - 995 Words

Statement of Purpose (new text in red) Introduction Chemical engineering fascinated me at an early age, as the transformation of many different, potentially conflicting compounds could be brought together to create entirely new products. The greatest innovations in consumer packaged goods (CPG), medicines and most recently in the areas of sustainability and environmental engineering can all be attributed to the core concepts of chemical engineering (Glavic, 2006). The continual evolution of green technologies can be traced back to the innovations made possible through chemical engineering. Ive seen firsthand how these innovations drastically improve peoples lives while also improving the environment and leading to a much greater level of prosperity in our nation as well. Another facet of my fascination with chemical engineering comes from the exceptional economies of scale attained in refinery operations. It is remarkable how effective the refinery operations are of oil and gas producing nations including their ability to drastically reduce the costs of fuel for millions of people. The value of engineering management in making refinery operations more efficient can also lead to a rapid reduction in energy costs, making energy more affordable for more members of our country as well (Lannes, 2001). The innovations evident in products and processes sparked my interest and enthusiasm for this area, and continued to fuel my efforts over the long-term. 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Characteristics of a Poet Lawrence Ferlinghetti Essay Example For Students

Characteristics of a Poet: Lawrence Ferlinghetti Essay Characteristics of a Poet: Lawrence Frightening Throughout the various poems composed by writer Lawrence Frightening there emerges a series of defining characteristics of his style. Most If not all of his poems are written In free verse style that doesnt follow traditional poetic composition. He has odd breaks and varying line lengths that serve as transitions and guides to his respective pieces. This was evidenced quite obviously in his poem Dont let that horse which had no punctuation or repetitious structure to force any pauses or enjambment between such lines as And became famous/And kept on painting/The Horse With Violin In Mouth. Frightening shows an astounding ability in this regard to take structure and use It to gulled the piece while maintaining a free flow that Isnt nailed to the paper. Rather that nail it, he loosely binds the piece to Itself with irregular accents and rhythms and uneven rhyme schemes that develop the meaning far beyond face value. The structure though, doesnt only hold the piece together as a tool, it also can serve to further illustrate as in The Changing Light where the line organization is nebulous and similar to fog and mist. In the effective use of these tools Frightening is able to manipulate most If not every aspect of his poetry to serve the meaning and depth as a whole. In practically every Lawrence Firelight poem there Is a strong visual element to the piece that is tangible but figurative. The poems begin with solid examples of the physical world such as the ocean in A Vast Confusion that are a surface meaning of the poem that can be understood by anyone. Below that though, is a subjective and often deeper level of understanding that lends the poem a more profound meaning ether than Just a surface view with a pretty picture. In the Instance of A Vast Confusion the ocean was characteristic of the continuous onslaught of sounds that were tethered together by a deep universal hum that exemplified and Illustrated a pattern to the cacophony he was hearing. The key characteristic when identifying a Frightening poem is the commonplace visuals he gives of the surroundings as if from the perspective of a ordinary person. In his poem Number 20 he speaks of the Jellybeans being part of a state of unreality that Is firmly illustrated with the subtle but Important semi-gloom/of that September afternoon. With the few rhymed words within those three lines the setting and mood was established as a gloomy afternoon in a candy store that is quite visual and very common. This underlying tool of Firelights readily establishes him as a talented poet and a man that is gifted with the understanding of brevity when it comes to description. Yet another characteristic of Frightening is his Beat generation themes regarding the status quo and mainstream poetry. In many of his poems including Bird With on political and social issues claiming that the government is Two right wings and that underwear is like an opinion. Though either of these references seems absurd he carries this conceit, especially with the underwear, to the point of some people being bound by their opinion-underwear and unable to escape the recurring pattern of interchangeable leaders of the nation. The fact that he would say things in his works that others wouldnt places him in the Bohemian/Beat era of poetry that was starting when he began writing. He even steals some of his techniques from writers like E. E. Cummings and James Joyce with incorrect syntax and selective capitalization to emphasize words and phrases. His adaptation of these styles works o make his poetry more of a reader-based interpretation of such mystic lines as and stretch/her sweet anatomy/let fall a stocking in Number 8. The simple point of view established by the observation of the woman pulls the reader into the bed as the man but the shifty structure and the lines that stand as their own serve to reinforce this by pulling the reader into the mind of the man. .u30812824e2c74599c5e3a4efa05f6772 , .u30812824e2c74599c5e3a4efa05f6772 .postImageUrl , .u30812824e2c74599c5e3a4efa05f6772 .centered-text-area { min-height: 80px; position: relative; } .u30812824e2c74599c5e3a4efa05f6772 , .u30812824e2c74599c5e3a4efa05f6772:hover , .u30812824e2c74599c5e3a4efa05f6772:visited , .u30812824e2c74599c5e3a4efa05f6772:active { border:0!important; } .u30812824e2c74599c5e3a4efa05f6772 .clearfix:after { content: ""; display: table; clear: both; } .u30812824e2c74599c5e3a4efa05f6772 { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .u30812824e2c74599c5e3a4efa05f6772:active , .u30812824e2c74599c5e3a4efa05f6772:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .u30812824e2c74599c5e3a4efa05f6772 .centered-text-area { width: 100%; position: relative ; } .u30812824e2c74599c5e3a4efa05f6772 .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .u30812824e2c74599c5e3a4efa05f6772 .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .u30812824e2c74599c5e3a4efa05f6772 .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .u30812824e2c74599c5e3a4efa05f6772:hover .ctaButton { background-color: #34495E!important; } .u30812824e2c74599c5e3a4efa05f6772 .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .u30812824e2c74599c5e3a4efa05f6772 .u30812824e2c74599c5e3a4efa05f6772-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .u30812824e2c74599c5e3a4efa05f6772:after { content: ""; display: block; clear: both; } READ: A Small Elegy EssayThe thought-like phrase let a stocking fall with its simplicity and brevity lend to the feel that it was a fleeting observation or perhaps wish. While some verses in his poems hold the face value interpretation many have a deep meaning that is created with the Cummings-sees style. Not only though is Frightening identifiable by his views, he is identifiable by his viewpoints. His description of life as in Dog and No. 20 evoke a feel of a man walking the streets speaking out the truths of common experience rather than an objective distanced dictation. Moreover his poems read like an oral presentation The pennyworths beyond the Ellis where I first/fell in love/with unreality as one might find from a man of the streets. The conversational style and good natured erase are indicative of a public reading situation that an open air poet would write to. The alliterations and repetitions such as and balancing on beams/above a sea of faces/paces his way/to the other side of day from Constantly Risking Absurdity are another identifying characteristic of Frightening when coupled with the haphazard and hidden rhyme style and shifting meter that he is known for. He champions the idea of informal poetry modeled after the vernacular of the people with his simple lines from Sometime During Eternity Him Just hang there/on His Tree/looking real Petered outland real cool. In this instance the crucifixion of Christ is related with phrasing indicative of the common language Frightening would talk in though it is oversimplified to make it a bit more obvious. The point of view established by the diction and structure of the poem coupled with the selective detail is perhaps one of Lawrence Firelights most powerful attributes. Alas perhaps the most interesting and subtle characteristic of the collective works of Lawrence Frightening is the innate ability to describe with little to no actual description. In the poem Wild Dreams of a New Beginning the special attention to correctors and relationships between them is beautiful. The breathless hush on the freeway and the calm candlelight couples establish a peaceful setting that carries a degree of suspense as the artery of travel, the freeway, is silent. The mood and the setting of the piece were both illustrated in two simple lines that are later twisted into a deathless hush on the freeway that initiates the turn of events. His civilization act as very basic pieces of information that change the poem from calm to tumultuous within a single stanza. Notable though, is the very little information that s given about the destroyer or the civilization its wiping away yet the depth of the setting and feeling of the piece. Frightening is notorious in all these analyzed poems for being able to build a beautiful frame for a work and letting the imagination of the reader fill in everything else not unlike Hemingway short stories. This ability to write between the lines is what identifies him as a master poet and writer. Whether it is the structure of him poems or the themes they embody, there are certain defining characteristics of Lawrence Firelights poems that set them apart from all others.