Lowering the Freezing Point of Water

Lowering the Freezing Point of Water It is common knowledge that the freezing point of pure water is at 0 degrees centigrade or 32 degrees ferinheight. However, is it possible to keep water in its liquid state below that freezing point? It is indeed possible, and people have been using this principle for centuries! Traveling back to the 1600s we find King Charles I of England dining with his lords and ladies. The final course is the epicurean delight of ice cream. It is doubtful that King Charles I understood the scientific principle of depressing the freezing point of a solution; nevertheless, at that time it was impossible to make ice cream without freezing the crà ¨me by depressing the freezing point of water below 0 degrees centigrade (Zinger, 2005). Today, principalities spread salt on icy roads in order to â€Å"melt† the ice. In actuality, the salt is merely depressing the freezing point of the water, allowing the roads to remain ice free even while the temperatures are below 0 degrees centigrade. To comprehend freezing point depression, you must first understand freezing point. Simply put, it is considered the temperature at which a liquid changes into its solid phase. However, it can also be thought of as the temperature at which the liquid and solid phases are at equilibrium with the atmospheric, or vapor, pressure around it. Freezing occurs as water molecules become ordered into a crystalline lattice. Scientists have long known about the phenomenon that when you add a solute to a solvent, the freezing point lowers, or depresses. Freezing point depression is a colligative property. Colligative properties are the properties of solutions that depend on the number of molecules in a solvent. It does not depend on the properties of the individual molecules in the solution (Prentice-Hall, 1972). As an example, when you create a solution by adding sodium chloride as the solute, to the solvent of water, the freezing temperature of the solution decreases. The increase of the number of solute particles of the solution interferes with the development of the crystalline structure, therefore the freezing process is delayed (Newton, 1999). Freezing point depression can be expressed mathematically as: ΔT = i Kf m. The ΔT equals change in temperature, i equals the number of particles into which the solute dissociates, m equals the moles of the solute per kilogram of solvent, and Kf equals the molal freeing point constant (for water, Kf = 1.853 C/m) (thinkquest, 2010). As discussed, solutes interfere with the shifting of a liquid to a solid state. The colligative properties relate to the number of solute particles in a solution. The greater the solute particles there are in a solution, the greater the decrease in freezing temperature. If 10 grams of sodium chloride were added to 100 grams of water, the freezing point would drop to -5.9 degrees centigrade. However if 10 grams of sucrose were added to 100 grams of water, the water solutions freezing point would only drop to -0.56 degrees centigrade. Why the dramatic difference between the two? After all, the same amount of sucrose and sodium chloride was added to the same amount of water. The answer lies in the number of particles in each solute. There are more particles in 10 grams of sodium chloride then there are in 10 grams of sucrose. Sucrose, C12 H22 O11, has a molecular weight of 342.3 grams per mole. Sodium Chloride on the other hand, has a molecular weight of 58.44 grams per mole. Sodium Ch loride has almost six times as many particles than sucrose has in the same number of grams. Therefore, the sodium chloride solution has a lower freezing point than the sucrose solution (Chemistry Explained, 2010). Not only is it possible to quantify the depression of the freezing point of a solution, it is possible to predict how far the freezing point will be decreased. According to the principles of the colligative properties, it doesnt matter what the physical properties of the solute added to the solution may be. The only determining factor is the number of particles in the solution. Therefore, if you double the amount of sodium chloride in a solution, the depression of the freezing point will be double the original solution. The original question of, â€Å"is it possible to keep water in its liquid state below that freezing point?†, has most assuredly been answered with a resounding yes. Not only can it be lowered, that lowering can be understood, quantified and predicted. In the experiment phase of this project, the scientific method will be used to assess the validity of this research. King Charles I of England would be surprised to know that his epicurean delight of ice cream paved the way for the discoveries of colligative properties and lowering the freezing point of water. Bibliography A Brief History of Ice Cream, http://www.zingersicecream.com/history.htm Colligative Properties, http://www.chemistryexplained.com/Ce-Co/Colligative-Properties.html Solutions and Colligative Properties: Colligative Properties, http://library.thinkquest.org/C006669/data/Chem/colligative/colligative.html W.J. Moore, Physical Chemistry Prentice-Hall 1972

What’s Under my Bed :: Free Essay Writer

What’s Under my Bed As I cleaned and rearranged my room one day, I slid my bed forward and found my childhood teddy bear. When I first saw him I could not believe I still had him. It looked much different than I remember. It was covered in dirt and grime. It smelled like a dusty, mildew-infested basement. I remembered the bear’s name; his name was Horace. I named him after myself. Horace lay there on my floor; his body stretched out twenty-four inches across my floor. He is wearing my old blue denim Oshkosh overalls. The overalls’ appearance reminds me of pants that had been run through the washer several hundred times. Atop Horace’s head are two half brown, half mocha, orange slice shaped ears. The right ear has an inch slit where a sliver of white thread hangs out. He has a large orange-peach head like a scrap of metal going through the first stages of oxidation. The soft fur on his head is hard and matted on the end where sticky candy used to lie. He has one small half marble, black eye on the right side. On the left side he has a hole where fluffy dirt colored cotton hangs out. The left side also has a dark brown spot; the spot reminds me of a cartoon character with a black eye. Just under the left eye on his puffy, beige-colored cheek he has two dark brown freckles. In between his right eye, and left hole, he has a patch of hair missing, wh ich reveals tightly threaded fish netting holding the stuffing inside. An inch below that is his flat, oval shaped nose. I can see teeth marks made by a teething Child. Horace’s head attaches directly to his torso; there is no neck in between. There is an upside down beige triangle patch of fur top of his chest his chest. His upper body is dark brown, like the patch around his eye. The brown flows out to the outstretched, five-inch arms. It comes to an end at the last two inches of the arms where it changes to an orange-peach color again. His lower section is hidden in the overalls. The left leg of the overalls is cuffed just above the foot.

History of DES Essay

DES was proposed in 1975 and approved in 1977 as a federal information processing standard. It was criticized by the people who felt that it’s 56 key lengths to be insecure. In spite of this, DES remained a strong encryption algorithm until mid 1990. In the year 1998 summer, the insecurity of DES was demonstrated when a $ 250,000 computer which was built by the electronic frontier foundation decrypted a DES-encoded message in 56 hours. This was improved in the 1999 to 2002 hours through a combination of 100,000 networked personal computers and the EFF machine. DES remains a de facto standard unless a substitute is found (Landau, 2000, p. 341). A certified DES is obtained from the National Institute of Standards and Technology (NIST). This Advanced Encryption Standard (AES) works in three key lengths: 128, 192, and 256 bits. The publication of DES indicated a new era in cryptography. The development in the community of public cryptographers was enhanced by having an algorithm availability of study that the national security agent certified to be secure (Landau, 2000, p. 341). The (DES) Data Encryption Standard. A system that encrypts quickly but is essentially what is impossible to break is all what cryptographers have always wanted. Public key systems have captured the imagination of mathematicians because of their reliance on elementary number theory. Public key algorithms are used for establishing a key because they are too slow to be used for most data transmissions. Private key system does the encryption because they are typically faster than public key ones (Landau, 2000, p. 341). The data Encryption Standard (DES) workhorse uses private key algorithm besides relying on cryptographic design principles that predate public key. The RC4 in web browsers and the relatively insecure cable TV signal encryption are an exception to DES. DES is the most widely used public cryptosystem in the world. It is the cryptographic algorithm which is used by banks for electronic funds transfer. It is also used for the protection of civilian satellite communications. Still, a variant of DES is used for UNIX password protection. There are three operation of the DES which involves XOR, substitution and permutation. The DES is an interrelated block cipher and a cryptosystem on a block of symbols that sequentially repeats an internal function which is called a round. It encrypts data by the use of a primitive that operates on a block of symptoms of moderate size. Self invert ability is also essential to enable one of the objects to encrypt and decrypt. When encrypting ordinary text, DES begins by grouping the text into 64 bit block. A number of operations are performed by the DES on each block (Landau, 2000, p. 343). The transformation of how the block is to be carried out is determined by a single key of 56 bits. DES iterates sixteen identical rounds of mixing; each round of DES uses a 48-bit sub key. The DES begins with an initial permutation P and ends with its inverse. The permutations are of minor cryptographic implications but forms part of the official algorithm. The selection of sub keys starts by splitting the 56-bit key into two 28-bit halves and rotating each half one or two bits; either one bit in rounds 1, 2, 9, and 16 or two bits otherwise. The two halves are put back together and then 48 particular bits are chosen and put in order (Landau, 2000, p. 343). Attacks of DES The selection of DES was followed by protests in which case some of the researchers appeared to object to the algorithm small key space. Investors in the key public cryptography claimed that a DES encoded message could be broken in about a day by a $ 20 million machine made up of a million specially designed VLSI capable of searching one key per microsecond while working in parallel. The use of a meet in the middle attack to break a four round version of DES did not extend past seven rounds (Landau, 2000, p. 345). This is evidence that, for all these attacks none of them posed a serious threat to the DES. Other attacks on the DES were performed to poke harder to the innards of DES. This brought anomalies which led to the first attacks that were seen to be more theoretically better than exhaustive search. The attacks were against the block structure system and the need of all block-structured cryptosystems needed to be designed to be secure against differential and linear cryptanalysis. There is a strong attack to DES which is differential cryptanalysis. This is apparently known to the algorithms designers. In order to design a secure cryptosystems, there is a need for a mixture of well known principles, some theorems and the presence of some magic. Attacks on a cryptosystem fall into two categories which are passive attacks and active attacks. The passive attacks are the ones which adversely monitors the communication channel. They are usually easier to mount although they yield less. The active attacks have the adversary transmitting messages to obtain information (Landau, 2000, p. 342). The aim of the attackers is to determine the plaintext from the cipher text which they capture. A more successful attack will determine the key and thus compromise a whole set of messages. By designing their algorithms, cryptographer’s help to resist attacks such as cipher text only attack whose adversary has access to the encrypted communications. The known plain text attack which has its adversary has some plain text and its corresponding cipher text. The third attack which can be avoided is the chosen text attack and its adversary chooses the plain text for encryption or decryption. The plain text chosen by the adversary depends on the cipher text received from the previous requests (Landau, 2000, p. 342).

Understanding Present and Past Participles

In  traditional English grammar, a participle is a  verbal that typically  ends in -ing (the present participle)  or -ed (the past participle).  Adjective:  participial. By itself, a  participle can function as an  adjective  (as in the sleeping baby or the damaged pump). In combination with one or more  auxiliary verbs,  a participle can indicate tense, aspect, or  voice.  Ã‚   Present participles end in -ing (for example,  carrying, sharing, tapping). Past participles of regular verbs end in -ed (carried, shared, tapped). Past participles of irregular verbs have various endings, most often -n or -t (broken, spent). As linguists have long observed, both of these terms—present and  past—are misleading.  [B]oth [present and past]  participles are used in the formation of a variety of complex constructions (tenses) and can . . .  refer to  past, present, or future time (e.g., What had they been doing? This must be drunk soon).  Preferred terms are -ing form (which also includes gerund) and -ed form/-en form (Oxford Dictionary of English Grammar, 2014). EtymologyFrom the Latin, share, partake, participate Examples of Present Participles Ahead of Perenelle, a crowd gathered around a young man with a  dancing bear. (Stephen Leigh, Immortal Muse. DAW, 2014)Newport harbor lay stretched out in the distance, with  the rising moon  casting a long, wavering track of silver upon it. (Harriet Beecher Stowe,  Uncle Toms Cabin, 1852)Drawing on my fine command of the English language, I said nothing. (Robert Benchley)The ducks come on swift, silent wings, gliding through the treetops as if guided by radar, twisting, turning, never touching a twig in that thick growth of trees that surrounded the lake.(Jack Denton Scott, The Wondrous Wood Duck. Sports Afield, 1976) Examples of Past Participles During the thunderstorm, the frightened cat hid under the bed.[T]he clock, its face supported by plump cupids of painted china, ticked with a small busy sound. (Robert Penn Warren, Christmas Gift. The Virginia Quarterly Review, 1938)The new home stood beside the macadamized new road and was high and boxlike, painted yellow with a roof of glittering tin. (Elizabeth Bishop, The Farmers Children Harpers Bazaar, 1949)One January day, thirty years ago, the little town of Hanover, anchored on a windy Nebraska tableland, was trying not to be blown away. (Willa Cather, O Pioneers! 1913)The Bibles Jezebel came to an ugly end. Thrown from a balcony, trampled by horses, and devoured by dogs, the middle-aged queen has had few good days since. (Review of Jezebel: The Untold Story of the Bible’s Harlot Queen by Lesley Hazleton. The Week, November  29, 2007)I believe in broken, fractured, complicated narratives, but I believe in narratives as a vehicle for truth, not simply as a form of en tertainment. (Stephen Greenblatt, Will in the World: How Shakespeare Became Shakespeare. W.W.  Norton, 2004) Source of the Terms Present and Past [There is] an apparent contradiction  in  our selection of terminology for  the present and past  participles. We have described the participles as non-tensed, and yet we have used the terms present and past to distinguish them. These  terms, in fact, derive from  the most characteristic uses of the participles, in constructions such as: Sue has made a sponge cake Sue is making a sponge  cake In (1) the making of the cake is located in past time and in (2) it is located in present time. Note, however, that it is not the participles themselves that suggest this difference, but rather the total contructions. Consider: Sue was making a sponge cake Here the making of the cake is certainly not located in the present but rather, as was indicates, in the past.  We thus wish to retain the  traditional terms on the grounds that they relate to the characteristic uses of the two forms, but at the same time insist that the forms are  tenseless: there is no  tense contrast between them. -(Peter Collins and Carmella Hollo, English Grammar: An Introduction, 2nd ed. Palgrace Macmillan,  2010) Examples of Present and Past Participial Phrases Leaking from restaurant walls, beamed into airports as they landed and automobiles as they crashed, chiming from steeples, thundering from parade grounds, tingling through apartment walls, carried through the streets in small boxes, violating even the peace of desert and the forest, where drive-ins featured blue musical comedies, music at first overwhelmed, then delighted, then disgusted, and finally bored them (John Updike, The Chaste Planet. Hugging the Shore: Essays and Criticism. Knopf, 1983)   Participles as Quasi-Adjectives As modifiers of  nouns, present and past participles of verbs function very much like adjectives. Indeed, they are sometimes regarded as adjectives when they modify nouns. A present participle attributes a quality of action to the noun, which is viewed as undertaking the action, as retreating of legs in [109]. A past participle views the noun as having undergone the action expressed by the participle, as prefabricated of buildings in [110]. [109] . . . the cripples envy at his straight, retreating legs[110] various prefabricated buildings Thus, the present is an active participle and the past is a passive participle.(Howard Jackson, Grammar and Meaning. Longman, 1990)Participles as Verbs and Adjectives Participles occupy an  intermediate position between verbs and adjectives. Like verbs of a clause, participles may function as predicates and take complements and adjuncts, in fact they refer to situations.  Since they are atemporal, they can, like adjectives, also function as modifiers of nouns.(Gà ¼nter Radden and Renà © Dirven, Cognitive English Grammar. John Benjamins, 2007) Participles as Sentence Openers When the  participle is a single word—the verb with no complements or modifiers--it usually occupies the adjective slot in preheadword position: Our snoring visitor kept the household awake.The barking dog next door drives us crazy. . . . While the single-word participle generally fills the preheadword adjective slot, it too can sometimes open the sentence—and with considerable drama: Exasperated, she made the decision to leave immediately.Outraged, the entire committee resigned. Youll notice that both of these openers are past participles, rather than the -ing present participle form; they are, in fact, the passive voice. -(Martha Kolln, Rhetorical Grammar. Pearson, 2007) Pronunciation: PAR-ti-sip-ul