Surface Chemistry Essay Example for Free

Surface Chemistry Essay It is the phenomenon in which a substance is uniformly distributed all over the surface. Difference between adsorption and absorption: Absorption (i) It is the phenomenon in which a substance is uniformly distributed throughout the bulk of the solid. (ii) It is a bulk phenomenon. (iii) The concentration is uniform throughout the bulk of solid. Adsorption (i) The accumulation of molecular species at the surface rather than in the bulk of a solid or liquid is termed as adsorption. (ii) It is a surface phenomenon. (iii) The concentration of adsorbate increases only at the surface of the adsorbent. 7. 8. Sorption: When adsorption and absorption take place simultaneously, it is called sorption. Enthalpy or heat of adsorption: Adsorption generally occurs with release in energy, i. e. , it is exothermic in nature. The enthalpy change for the adsorption of one mole of an adsorbate on the surface of adsorbent is called enthalpy or heat of adsorption. 9. Types of adsorption: Get the Power of Visual Impact on your side Log on to www. topperlearning. com 2 a. Physical adsorption or physisorption: If the adsorbate is held on a surface of adsorbent by weak van der Waals’ forces, the adsorption is called physical adsorption or physisorption. . Chemical adsorption or chemisorption: If the forces holding the adsorbate are as strong as in chemical bonds, the adsorption process is known as chemical adsorption of chemisorption. It is highly specific (ii) It is irreversible (iii) The amount of gas adsorbed is not related to critical temperature of the gas. Physical adsorption (Physisorption) (i) It is non-specific (ii) It is reversible (iii) The amount of gas depends upon nature of gas, i. e. easily liquefiable gases like NH3, CO2, gas adsorbed to greater extent than H2 and He. Higher the critical temperature of gas, more will be the extent of adsorption. (iv) The extent of adsorption increases with increase in surface area, e. g. porous and finely divided metals are good adsorbents. (v) There are weak van der Waals’ forces of attraction between adsorbate and adsorbent. (vi) It has low enthalpy of adsorption (20 – 40 kJ mol-1) (vii) Low temperature is favourable. (viii) No appreciable activation energy is needed. (ix) It forms multimolecular layers. 11. (iv) It also increases with increase in surface area. v) There is strong force of attraction similar to chemical bond. (vi) It has enthalpy hea t of adsorption. High temperature is favourable. (viii) High activation energy is sometimes needed. (ix) It forms unimolecuar layers. Factors affecting adsorption of gases on solids: a. Nature of adsorbate: Physical adsorption is non-specific in nature and therefore every gas gets adsorbed on the surface of any solid to a lesser or greater extent. However, easily liquefiable gases like NH3. HCl, CO2, etc. which have higher critical temperatures are absorbed to greater extent whereas H 2, O2, N2 etc. re adsorbed to lesser extent. The chemical adsorption being highly specific, therefore, a gas gets adsorbed Get the Power of Visual Impact on your side Log on to www. topperlearning. com 3 on specific solid only if it enters into chemical combination with it. b. Nature of adsorbent: Activated carbon, metal oxides like aluminum oxide, silica gel and clay are commonly used adsorbents. They have their specific adsorption properties depending upon pores. c. Specific area of the adsorbent: The greater the spec ific area, more will be the extent of adsorption. That is why porous or finely divided forms of adsorbents adsorb larger quantities of adsorbate. The pores should be large enough to allow the gas molecules to enter. d. Pressure of the gas: Physical adsorption increases with increase in pressure. 12. Adsorption isotherm: The variation in the amount of gas adsorbed by the adsorbent with pressure at constant temperature can be expressed by means of a curve is termed as adsorption isotherm. 13. Freundlich Adsorption isotherm: The relationship between x and m pressure of the gas at constant temperature is called adsorption isotherm and is given by ? k P 1 /n (n ? 1) m Where x- mass of the gas adsorbed on mass m of the adsorbent and the gas at a particular temperature k and n depends upon the nature of gas and the solid x first increases with increase in pressure at low pressure but becomes m independent of pressure at high pressure. Get the Power of Visual Impact on your side Log on to www. topperlearning.

The Mantle of the Prophet Essay -- Islamic History, Mothhahedeh

Roy Mottahedeh is a professor of Islamic history at Harvard University. He has written widely in the history of Islam and religion. The Mantle of the Prophet is one of the books that Mottahedeh wrote. In this book, Mottahedeh covers different aspects that include Islamic faith, Iranian city of Qom, traditions derived from the history of Iran, political change in Iran and secular Islamic learning among other issues. Ali Hashemi and Parviz studied together in the same elementary school courtyard. However, each of them took different turns. This paper is a review of The Mantle of the Prophet by Roy Mottahedeh. It will discuss the similarities and differences of the ideologies of Hashemi and Parviz and their oppositions to the Shah. It will also discuss their social backgrounds and cultural influences on their outlook of the world. The book begins with a detailed description of Qom, an Iranian city where Ali Hashemi, the main point of reference, in the book was born. Mottahedeh also describes the Shi’ite faction of the Islamic faith that entails learning and tradition, in Iran. Mottahedeh managed to introduce readers to political climate, history and tradition from the middle of the twentieth century. Mottahedeh recounts the life of Ali Hashemi from his childhood through his education into adulthood. Ali Hashemi is the contemporary mullah of Qom. The book portrays Ali Hashemi as an alias of a mullah in the University of Tehran. This presents Ali Hashemi as a scholar just like Parviz. However, Hashemi is still engrossed in Islamic religion unlike Parviz. Mottahedeh used Hashemi to bring a clear picture of culture and history in Iran, in different times. Mottahedeh used Hashemi to create a scenario that depicts trends and issues that i... ...ries and the 1979 revolution. The author presents Iran through the leadership of mullahs and shah tradition. The book has rich information covering the history of Iran. Mottahedeh managed to develop an impressive book that satisfies the curiosity of a reader wanting to understand the history, culture and political atmosphere of Iran through the eighteenth, nineteenth and twentieth century. Roy Parviz Mottahedeh and Ali Hashemi represent two views of Islamic learning and Iranian history and culture. While Ali Hashemi represents a religious view of Islamic learning and history of Iran, Parviz represents a secular view of Islamic learning and ambiguity of culture in Iran. The two views help to bring out the ways in which Islamic religion and culture influenced political atmosphere, in Iran especially at a time when politics in Iran was shaped by religion.

Effectiveness of Racial Profiling in Countering Terrorism

[Student's Name] [Professor's Name] [Subject Code and Title] Is Racial Profiling an Effective Counter Terrorism Measure? The September 11 terror attack on the American soil was followed by a successive wave of events that were aimed at countering terrorism. As the global engagement on terrorism intensified, racial profiling became more pronounced along the corridors of counter-terrorism. Conversely, the employment of racial profiling as an instrument for detecting terror suspects and countering terrorism has elicited sharp criticism from different quarters.Even as protagonists of racial profiling reiterate its effectiveness in combating terrorism, dissenting voices lament the flagrant human rights violations and racial segregations borne of racial profiling. This paper critically examines the issues surrounding racial profiling in order to form a benchmark upon which the effectiveness of racial profiling in countering terrorism can be measured. The September 11 attacks on the US soi l, which was one of the single worst acts of terrorism in the world's history, led to the re-emergence of racial profiling in full force.In a desperate effort to bring to book the perpetrators of these attacks, security agencies in the US developed prejudice on Middle-Easterners. These prejudices were then codified into law including additional security measures for Arabs and Muslims leaving and entering the US territory. It is against this backdrop that racial profiling gained prominence not only in the US but also among its allies. This then raises a very pertinent concern as to whether racial profiling is effective in countering terrorism across the globe.Security organs more often than not have based detention and interdiction of suspects primarily on the basis of their race, ethnicity and/or religion. Pickering et al argue that racial profiling occurs against the belief that certain minority groups are more likely to engage in unlawful behavior. They further posit that integrat ing national security into law has opened up the possibility that racial profiling is inevitable in predicting crime and identifying potential perpetrators of crime.Profiling is however problematic in terms of its effectiveness given the fact that it is not firstly correlated statistically to risk. Secondly, racial profiling is ineffective in substantially narrowing down a pool of potential suspects (60). Therefore, profiling of suspects fails to meet professional law enforcement principles but instead reflect prejudice and discrimination. Nevertheless, the biggest concerns over profiling lie in the invasion of privacy as well as the erosion of fundamental civil liberties.The US has been on the forefront in advocating for the sharing of Passenger Name Records (PNR) information in an effort to single out possible terror suspects. However, this action invariably subjects individuals of particular ethnicities and religions to additional security checks consequently giving leeway to arb itrary discrimination (Muffler 241). What authorities do is basically identify names on the PNR that are Muslim or Arabic in nature. With the perception that Arabs and Muslims are potential terror suspects, they subject bearers of such names to more rigorous security screening.This act does not only discriminate affected individuals but it also produces a large number of false positives. Pickering et al have ascertained that large numbers of false positives divert resources needed to enhance more productive law enforcement activities. Moreover, false positives draws attention away from real threats and this is welcome news for terrorists. To that respect, racial profiling becomes self-defeating in the sense that it overlooks mainstream target groups thus ignoring the real danger of homegrown non-target terror groups (62).In the recent past, we have had terror attacks instigated by native citizens who have been either inspired by radical religious teachings or who are angry with thei r governments for reasons known to themselves. These individuals are never prioritized by the authorities thus pose a greater danger to national security. Over-emphasis on foreigners paves way for homegrown extremists to plan and execute terror attacks undetected. It is therefore a morally repugnant practice to target individuals as terror suspects based on their race and/or religion.Not all Muslims are terrorists and neither are all people of Arabic origin terrorists. It is really fallacious to generalize Muslims and Arabs as terrorists based on religious and ethnic prejudices. This then means that these individuals who would have otherwise provided intelligence on terror activities become sympathetic to terror groups with whom they share racial and religious inclinations. In the long run, racial profiling degrades social cohesion; it fuels animosity and ends up instigating more terror attacks that it intended to counter in the first place (Pickering et al 62).Racial alienation in the wake of racial profiling has given rise to a new phenomenon referred to as social terrorism. Intolerance experienced in society today has left victims of racial profiling with indelible marks of acute, episodic and vicarious discrimination. Social terrorism shutters minds, bodies and souls with affected individuals developing serious spiritual disturbances. These disorders may include questioning the essence of living, cessation from religious practices as well as loss of vitality and aliveness.Spirituality in particular is at the heart of resilience to adversity among people of color. Attacking a person's spiritual beliefs therefore creates individuals prone to radical religious teachings. It is the victims of social terrorism that have been found to cause the worst atrocities against humanity since they have nothing to lose after all (Etiony 97). Profiling indeed increases the detection of terrorists attack in the short run. Through racial profiling, terror suspects have been apprehended before initiating their attacks.In the long run however, racial profiling creates the possibility of dangerous substitution. On the current trajectory, there is no empirical evidence whatsoever exploring the use of racial profiling as a counter terrorism measure. This means that we have no idea whether racial profiling is indeed bearing fruits in countering terrorism or not. What we are aware of is how racial profiling has negatively impacted those subjected to it (Center for Human Rights and Global justice 19).It is not my intention to ruffle people's feathers the wrong way or even stir still waters. To that respect, I will try my very best to keep friendly skies friendly by condemning terrorism unreservedly with the strongest words possible. Terrorism destabilizes democracies by attacking the life and liberties of citizens. It must be met with firmness and increased co-operation among democratic countries. However, inasmuch as we must counter terrorism, we must denounc e the escalation of barbaric acts that strike down innocent victims.People do not immigrate to foreign lands just to bomb them but they rather do so to appreciate the quality of life in these foreign countries. It is therefore incumbent upon the citizens of resident countries to welcome these foreigners and help them integrate in their communities. When all is said and done, it is imperative that we win the war on terrorism if we desire to make the world a peaceful haven. This war will not however be won through covert and coercive methods of intelligence gathering. Law enforcement agencies must desist from hiding their laziness and inefficiencies behind racial bigotry.What is needed is development of security structures for sharing intelligence between security agents and citizens on counter terror activities. Security agencies can no longer afford to guard terrorism as a top secret since terrorism affects all people regardless of their status in society. Fundamental rights must ne ver become casualties of the politics of fear that have characterized States' response to the war on terror. A faithful adherence to human rights incorporated in international, regional, and domestic law is the only sure way of securing and protecting all persons.Works Cited Center for Human Rights and Global Justice. Irreversible Consequences: Racial Profiling and Lethal Force in the War on Terror. NY: NYU School of Law, 2006. Print. Etiony, Aldarando. Advancing Social Justice Through Clinical Practice. NJ: Lawrence Eribaum Associates, 2008. Print. Muffler, J. Steven. Racial Profiling: Issues, Data and Analyses. NY: Nova Science P, 2006. Print. Pickering, Sharon, McCulloch and Wright-Neville David. Counter-Terrorism Policing: Community, Cohesion and Security. NY: Springer, 2008. Print.

America Has Been Faced With The Growing Obesity Epidemic.

America has been faced with the growing obesity epidemic. This is becoming very wide spread among all races and class levels due in part to the abundance of inexpensive food available and how easily people are becoming persuaded to but things they do not need. David Zinczenko published article â€Å"Don’t Blame the Eater†, Zinczenko argues that fast-food industries are not doing their job to provide clear enough nutritional information for hazardous food. The title of Zinczenko’s article, â€Å"Don’t Blame the Eater† really catches the reader’s attention and makes the reader feel defensive because they are the eater so it becomes a bit personal. I personally liked it because it gave a sense of â€Å"it’s not my fault â€Å"but also made me ask the question†¦show more content†¦In the other article, â€Å"The Supermarket: Prime Real Estate,† Marion Nestle claims that supermarket companies control people to buy goods by using some surprised strategies. I as the reader disagree and think the writers claim is weak because even though supermarkets are created in a way to persuade people to buy certain foods, one is more in control of what one needs to buy due to time and having an idea of what they need and came to the supermarket to buy in the first place. In other words, one goes to the supermarket with the intention of going to buy something whether it is milk, chicken, etc. So by saying â€Å"that supermarket companies control people to buy goods† it is a bit untrue to the reader. In order to provide a solid argument, Zinczenko was able to understand that his opposition believed the reason people were getting fat was due to a lack of personal responsibility rather than fast-food industries being responsible. Following the aftermath of lawsuits involving people suing McDonald’s for his or her own obesity, Zinczenko takes this and likens these lawsuits to, â€Å"middle-aged men suing Porsche for making them get speeding tickets†. Zinczenko then goes on to relate to his opposition by stating that he himself used to be one of these â€Å"portly fast-food patrons†. This not only allows the reader to see that Zinczenko understands hisShow MoreRelatedSuper Size Me, by Morgan Spurlock Essay1099 Words   |  5 Pagesnumerous problems, such as economic devastation, one major problem is often disregarded, growing obesity. As the American society keeps growing, so does growth of the fast food industry and the epidemic of obesity. In order to further investigate the main cause of obesity, Morgan Spurlock, the film director and main character, decides to criticize the fast food industry for its connection with obesity in America. In his documentary Spurlock performs a radical experiment that drives him to eat onlyRead MoreThe Epidemic Of Childhood Obesity In America. 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