Questions and Answers on Intermolecular Forces Essay Example for Free

Questions and Answers on Intermolecular Forces Essay Intermolecular forces written response Hexane and Water do not mix. When the two substances are combined they separate into layers in the same manner oil and water do. Explain why this is? Well to begin with this, these two things are very dissimilar. Water is considered polar and secondly hexane is considered non-polar. Polar and non-polar cannot mix together they are to different substances. Polar solutes will dissolve in polar solvents and non-polar solutes will dissolve in non-polar solvents, this is where the expression ‘like dissolves like’ comes from. When theses two substances are combined they form different layers and this is because hexane is denser then water. Another very important reason to remember is that water is only soluble with nitrogen, fluorine, and oxygen. These two liquids are said to be immiscible. Water and oil will not mix for the same reason water is polar and oil is non-polar and for the same exact reason they are not mixable in a solution. Methane, ammonia and water are chemically similar. Yet the three substances have very different boiling points. Explain why this is true? This is due to the bonding between the molecules. The stronger they are the hotter you must make the liquid to cause it to boil. Intermolecular forces are the forces between the molecules of a substance. If a substance has very strong intermolecular forces, it is likely to be a solid, and if it has very weak intermolecular forces it is more likely to be a gas, and this is because there would be less attraction among the molecules (strong intermolecular force=more attraction between molecules). As you know, when you boil something, you are changing it from a liquid to a gas which means you would want to decrease the attraction among the molecules of the substance by adding energy. If a substance has intermolecular forces that are stronger, you would need more energy to overcome the forces which means it would have a higher boiling point (higher boiling point=higher temperature=more heat=more energy). The opposite is also true. If a substance has weaker intermolecular forces, less energy is required to decrease the attraction among the molecules and therefore it would have a lower boiling point. Ammonia and water have higher boiling points due to hydrogen bonding. Methane has a low boiling point because it belongs to the weakest London dispersion forces.

Nitric Oxide (NO) and the Nervous System Essay -- Medicine Biology Res

Nitric Oxide (NO) and the Nervous System Better known as an environmental hazard, nitric oxide (NO) is produced in combustion engines and contributes to smog and acid rain and has been implicated in the catalytic destruction of the ozone layer (Lancaster;1992). Though NO is the bad-boy of the environment, it’s roles in the body are extremely diverse and in some instances can be deleterious or beneficial depending on the circumstances. NO has been connected with immune function, control of blood pressure and hypertension, impotence and penile erection, septic shock, insulin-dependent diabetes mellitus, and macrophage mediated destruction of oncogenic cells (Young;1993, Stroh;1992). However, its activities in the nervous system may be the most exciting discovery yet for this eclectic molecule (Koshland;1992). Due to NO’s radical structure, it is highly reactive and very short-lived within the body (6-15 sec.) making its detection difficult (Lancaster;1992); as such, it can therefore be synthesized only on demand since radicals are known to disrupt cellular homeostasis. NO is small and uncharged and it rapidly diffuses through cellular membranes from its site of synthesis making it in ideal intercellular paracrine-like messenger or poison (Lancaster;1992). In the body, NO reacts with redox metals such as copper, manganese, or the iron heme-like protein centers, and molecular oxygen forming nitrites and nitrates, the latter constituting the principal manner in which NO is inactivated in vivo (Snyder;1992). The enzyme which synthesizes NO, nitric oxide synthase (NOS), has been cloned and structurally resembles cytochrome P-450 reductase, possessing many sequence homologies and the same physical sites for binding of identic... ... in Cells. American Scientist, 80:248-259, May/June 1992. Murray, R. K., D. K. Granner, P. A. Mayes, and V. W. Rodwell. Nitric Oxide is the Endothelium Derived Relaxation Factor and is Also an Important Compound in the Nervous System. Harper’s Biochemistry, pp 657-658, Appleton & Lange, USA, 1993. Schuman, E. M. and D. V. Madison. A Requirement for the Intercellular Messenger Nitric Oxide in Lone Term Potentiation. Science, 254:1503-1506, Dec. 6, 1991. Snyder, S. H. and D. S. Bredt. Biological Roles of Nitric Oxide. Scientific American, 266:68-71+, May 1992. Snyder, S. H. Nitric Oxide: First in a New Class of Neurotransmitters. Science, 257:494-496, July 24, 1992. Stroh, M. The Root of Impotence: Does Nitric Oxide Hold the Key. Science News, 142:10-11. July 4, 1992. Young, S. The Body’s Vital Poison. New Scientist, 137:36-40, March 13, 1993. Nitric Oxide (NO) and the Nervous System Essay -- Medicine Biology Res Nitric Oxide (NO) and the Nervous System Better known as an environmental hazard, nitric oxide (NO) is produced in combustion engines and contributes to smog and acid rain and has been implicated in the catalytic destruction of the ozone layer (Lancaster;1992). Though NO is the bad-boy of the environment, it’s roles in the body are extremely diverse and in some instances can be deleterious or beneficial depending on the circumstances. NO has been connected with immune function, control of blood pressure and hypertension, impotence and penile erection, septic shock, insulin-dependent diabetes mellitus, and macrophage mediated destruction of oncogenic cells (Young;1993, Stroh;1992). However, its activities in the nervous system may be the most exciting discovery yet for this eclectic molecule (Koshland;1992). Due to NO’s radical structure, it is highly reactive and very short-lived within the body (6-15 sec.) making its detection difficult (Lancaster;1992); as such, it can therefore be synthesized only on demand since radicals are known to disrupt cellular homeostasis. NO is small and uncharged and it rapidly diffuses through cellular membranes from its site of synthesis making it in ideal intercellular paracrine-like messenger or poison (Lancaster;1992). In the body, NO reacts with redox metals such as copper, manganese, or the iron heme-like protein centers, and molecular oxygen forming nitrites and nitrates, the latter constituting the principal manner in which NO is inactivated in vivo (Snyder;1992). The enzyme which synthesizes NO, nitric oxide synthase (NOS), has been cloned and structurally resembles cytochrome P-450 reductase, possessing many sequence homologies and the same physical sites for binding of identic... ... in Cells. American Scientist, 80:248-259, May/June 1992. Murray, R. K., D. K. Granner, P. A. Mayes, and V. W. Rodwell. Nitric Oxide is the Endothelium Derived Relaxation Factor and is Also an Important Compound in the Nervous System. Harper’s Biochemistry, pp 657-658, Appleton & Lange, USA, 1993. Schuman, E. M. and D. V. Madison. A Requirement for the Intercellular Messenger Nitric Oxide in Lone Term Potentiation. Science, 254:1503-1506, Dec. 6, 1991. Snyder, S. H. and D. S. Bredt. Biological Roles of Nitric Oxide. Scientific American, 266:68-71+, May 1992. Snyder, S. H. Nitric Oxide: First in a New Class of Neurotransmitters. Science, 257:494-496, July 24, 1992. Stroh, M. The Root of Impotence: Does Nitric Oxide Hold the Key. Science News, 142:10-11. July 4, 1992. Young, S. The Body’s Vital Poison. New Scientist, 137:36-40, March 13, 1993.

IPSec Tunnel and transport Modes Essay

Computer networking security is one of the primary concerns of any network systems. In this case, protecting the data transferred between channels should be a primary concern for any entities that use networking. This article will discuss IPSec Tunnel and Transport Modes. IPsec is short for Internet Protocol Security. This is a special suite to secure the Internet protocol data transfers and communication by encrypting each packet of data stream. IPsec may also include protocols so that mutual authentication can be established between any agents during sessions of data transfers. One of the main reasons why IPsec is used is to protect the integrity of data that flows from one channel to another, say for example between a computer and a user or a computer to a server. What is IPSec transport mode? In this mode, only the payload or the data that the user transfers is encrypted for authentication (Technet Microsoft, 2005). The routing of data in this mode is intact so there is no modification possible. The transport schemes are always secured by a hash. Transport mode is commonly utilized for host-to-host transfers and communications. On the other hand, with the IPsec tunnel mode, the whole of the IP packet is encrypted and authenticated before communications happen (Technet Microsoft, 2005). It is encased into a newly generated IP packet with a new header. Usually, tunnel more is used to build a Virtual Private Network for such a network to network communications or host to network communications. The tunnel mode can be applied to any of the following: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2 (Technet Microsoft, 2005).

Using Ict for Distance Learning Essay examples - 3348 Words

Word count 3215 (word count 3000 words plus 10%) TASK 1 GOOD ICT SKILLS ARE FUNDAMENTAL TO THE FACILITATION OF A POSITIVE DISTANCE LEARNING EXPERIENCE. PRODUCE A REPORT WHERE YOU; 1. EVALUATE HOW YOU AS A STUDENT AND INDIVIDUAL CAN MAINTAIN EFFECTIVE COMMUNICATION WITH YOUR TUTOR DURING YOUR STUDIES As a student I can maintain effective communication with my tutor by using my ICT skills which allow me to access online distance study. I can access the internet, log into the College ‘On Campus’ home page, navigate through the link on the web site and read how to submit a question and to access my tutor’s response. I will be maintaining effective communication with my tutor by writing my reports and other assignments, by giving†¦show more content†¦Strengths (internal factors): Good self-discipline. Good motivation. Good ICT skills. Writing skills. Previous experience of studying alone (group therapy assignment following 1 week course at Bath University). Experience and enjoyment of study and of education. Level of education (honours degree). Level 3 Counselling Studies course experience and qualification. Having a clear goal to gain this qualification and work as a counsellor. Attention to detail. Ability to plan ahead and to work to a plan. Love of co mmunication. Desire to do well. My commitment to improve myself and my prospects. Weaknesses (internal factors): Being a perfectionist. Getting stuck in detail and overcomplicating this online study process and the aims of Units. Lacking the feedback gained from face to face communication particularly with my tutor and other students. Fear of not communicating clearly with my tutor. Opportunities (external factors): Access to ICT at home and work. Support from my employer and support from my partner. Support from College, tutor, other students, counsellors at work. 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