How to Calculate Freezing Point Depression

This example problem demonstrates how to calculate freezing point depression using solution of salt in water. Quick Review of Freezing Point Depression Freezing point depression is one of the colligative properties of matter, which means it is affected by the number of particles, not the chemical identity of the particles or their mass. When a solute is added to a solvent, its freezing point is lowered from the original value of the pure solvent. It doesnt matter whether the solute is a liquid, gas, or solid. For example, freezing point depression occurs when either salt or alcohol are added to water. In fact, the solvent can be any phase, too. Freezing point depression also occurs in solid-solid mixtures. Freezing point depression is calculated using Raoults Law and the Clausius-Clapeyron Equation to write an equation called Blagdens Law. In an ideal solution, freezing point depression only depends on solute concentration. Freezing Point Depression Problem 31.65 g of sodium chloride is added to 220.0 mL of water at 34  °C. How will this affect the  freezing point of the water?Assume the  sodium chloride completely dissociates in the water.Given: density of water at 35  °C 0.994 g/mLKf water 1.86  °C kg/molSolution:To find the  temperature change elevation of a solvent by a solute, use the freezing point depression equation:ΔT iKfmwhereΔT Change in temperature in  °Ci van t Hoff factorKf molal freezing point depression constant or cryoscopic constant in  °C kg/molm molality of the solute in mol solute/kg solvent.Step 1 Calculate the molality of the NaClmolality (m) of NaCl moles of NaCl/kg waterFrom the periodic table, find the atomic masses of the elements:atomic mass Na 22.99atomic mass Cl 35.45moles of NaCl 31.65 g x 1 mol/(22.99 35.45)moles of NaCl 31.65 g x 1 mol/58.44 gmoles of NaCl 0.542 molkg water density x volumekg water 0.994 g/mL x 220 mL x 1 kg/1000 gkg water 0.219 kgmNaCl moles of NaCl/kg watermNaCl 0.542 mol/0.219 kgmNaCl 2.477 mol/kgStep 2 Determine the van t Hoff factorThe van t Hoff factor, i, is a constant associated with the amount of dissociation of the solute in the solvent. For substances which do not dissociate in water, such as sugar, i 1. For solutes that completely dissociate into  two ions, i 2. For this example, NaCl completely dissociates into the two ions, Na and Cl-. Therefore, i 2 for this example.Step 3 Find ΔTΔT iKfmΔT 2 x 1.86  °C kg/mol x 2.477 mol/kgΔT 9.21  °CAnswer:Adding 31.65 g of NaCl to 220.0 mL of water will lower the freezing point by 9.21  °C.

HIV/AIDS Research Paper - 1253 Words

HIV/AIDS Throughout history, few illnesses have carried as much significance as Acquired Immune Deficiency Syndrome or AIDS. Similar human catastrophes have presented in our history such as, bubonic plague, leprosy and tuberculosis. All of these dreaded sicknesses have caused pain and suffering across cultures. Pain is associated with the physical distress of the patient, suffering is culturally distinctive, it describes the affliction of the human spirit and how community members cope with it. AIDS has given moral do-gooders a ripe opportunity to condemn others for behaviors which do not coincide with their perceived values. Globally, Americans have been blamed for creating the virus and spreading the disease worldwide. AIDS has†¦show more content†¦A majority of Americans have been exposed to or heard of marijuana. Marijuana is a common drug among all age groups of Americans. It was once legal and still popular. The US government and citizens have now raised the question if the par ty drug that is known to relax the body and mind should be legalized in the United for medicinal purposes. Marijuana helps cancer patients with pain during treatment, helps AIDS patients regain their appetites, and those with glaucoma have shown improvement in their condition. Currently, there is no cure for HIV/AIDS. If you are infected with the virus, you can receive drugs that will only slow the virus from destroying your immune system. However, there is no way of ridding the virus from your body. AIDS has weakened the confidence we have in the ability of experts to solve problems. This cultural value is blatantly evident in the model of care for AIDS patients. The bulk of care is focused on end stage interventions, when little can be done to extend the life of a patient. The victim becomes faceless medical record numbers, and are viewed in as failures of the medical system. 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Springtime in the Canterbury Tales Free Essays

Brooke Schweitzer Dr. O’Callaghan Eng 402 April 11, 2010 Springtime in The Canterbury Tales _See how the lilies of the field grow. †¦Yet I tell you that not even Solomon in all his splendor was dressed like one of these. We will write a custom essay sample on Springtime in the Canterbury Tales or any similar topic only for you Order Now -Matthew 6:28-29_ Springtime and beauty is inevitably linked in Chaucer’s Canterbury Tales. Chaucer uses the images of springtime from the very beginning of the prologue to promote the idea of renewal and overall joyfulness. Not only is it used to establish tone or theme in the prologue, but is also used closely with the descriptions of beauty for the tales that follow. Chaucer knew that that his readers would without hesitation identify with springtime and the idea of renewing ourselves for a new season, just like the pilgrims we read about. Anyone who reads the Canterbury Tales will find pilgrims who are not without faults going on a pilgrimage to a religious site looking to purify themselves. By placing them in springtime he has set up a direct contrast between what early Christians would have deemed a â€Å"holy† life and the ones led by the travelers. Found even in descriptions of beauty. The pilgrims stories are in way, asking us to look closely at our own nature and perhaps institute the idea of changing ourselves for the better. Chaucer uses an intense theme of springtime to promote the ideas of youthfulness and beauty. The most prominent example is in the very opening lines of the General Prologue, â€Å"Whan that April with his shoures soote/ The droghte of March hath perced to the roote/ And bathed every veyne in swiche licour† (Pg 41 line 1-3) In the beginning we have the opening of April. We know that it is the very beginning of the month because the second line mentions that â€Å"March hath pierced to the roote. Although many would say that this would mean there had been a â€Å"droghte† leaving things dry. When I read this line I considered the geographical weather patterns of Britian and concluded that it is always raining there. Even if the weather may have been different than the weather patterns we have there today, I assumed this to be a poetic way to say that March has completed it’s time. Along with the idea of the beginning of April, Chaucer tells us, â€Å"†¦With†¦ shoures soote/†¦And bathed every veyne in swiche licour. † So we have the imagery of everything being drenched in nutrient rich water. If everything is healthy, we can assume then that all the flowers, trees, grass and even the animals are now young and growing. Nature is awakening to a renewed season just like the pilgrims seeking renewal. The direct connection with our own self renewal along with nature is also mirrored in the descriptions of beauty. There are at least two examples of the women of the tales being described in terms of nature and the beauty of spring. In the Knights Tale Emily is described, â€Å"that fairer was to sene/ than the lylie upon his stalk green/ and fressher than the May with Floures newe. Again we are seeing this connection with not only a flower but again the idea of early May with new, young flowers. She is fresh, without blemish. She is indeed then the perfect idea of beauty. She does not need renewal or to change her nature. I believe that it is safe to say that in Chaucer’s time the image would be in the likness of freshness in terms of faith. Perhaps by describing Emily i n such a way the idea is that she is without sin. She is the perfect idea of a Christian lady. We see this again when the carpenter’s wife from the Miller’s Tale is described. Her looks are described at length until it is mentioned, â€Å"She was full moore blissful to see/ Than is the newe perejonette tree. † It is rather comedic that she is compared to a young tree. Unlike a young flower, a young pair tree is small and frail. It does not have many leaves or contain much fruit. In modern day terms it is difficult to see beauty in a tree. Trees are certainly something to marvel, but the point being that she is beautiful but is not without her faults. Unlike Emily from the former story, she has some rough edges. She is described as wild and flighty, By setting up these two different descriptions, Chaucer shows the reader that it is far better to be a â€Å"lily on a stalk of green† than â€Å" a new pear tree. We are seeing how the pilgrims want to change themselves to resemble something as fresh as a flower. It also worth considering the idea that since we define the beginning of spring when we first start to see flowers and leaves on trees, that perhaps Chaucer is saying that women are in control of love? By describing them in such a way could suggest that many of the women in the stories are in control of the situation. They can deny or accept a man. Although the connections between the springtime setting and the descriptions of beauty are subtle ones, they impact the overall theme that the reader takes away from the story. Like the pilgrims, we find ourselves being educated, entertained and chastised for our behavior. Springtime is a time of freshness and everything having a new start. Having an overall Christian audience for his story, Chaucer new they would relate to the freshness of spring. It is the same reason we celebrate Easter today. The entire tradition relies on the idea of being â€Å"born again† and rising up from who we are before. It is about letting go of the faults that hold us down. Just like the pilgrims in the stories we read, we reflect on the morals that the travelers tell each other. By the end we find that the common and rich alike have them and it is about who we as people believe we should behave, live and learn. How to cite Springtime in the Canterbury Tales, Essays

Most Prized Possesion free essay sample

Honestly, I have not really accomplished too much in my life but there is one achievement for which I received an award that depicts the effort and devotion I exerted into wrestling. Last year I was voted the most valuable junior varsity wrestler by my teammates and I received a trophy to honor my outstanding season. It is not a spectacular trophy. Rather, its value comes from a more personal sentiment, being a reminder that hard work and determination is the key to accomplishing any goals, mild or arduous. In my perspective, it is more an icon of my failure, with a hint of success. I understand that trophies normally do not represent someones failures. However, I realized that defeat is the quickest path to victory only after my second wrestling season had concluded because I recognized that continuously losing prepared me more than anything for my later matches. That is why I think of those failures and thank them when I look at my trophy. We will write a custom essay sample on Most Prized Possesion or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Now, my most prized possession sits proud on my bedside table, serving as a personal memento of my two-step journey as a wrestler. Having two brothers, I never did anything by whim because everything I took interest in was because of my brothers influences. One particular sport I got into was wrestling after my brother, Jonathan, started. Ill never forget the ardent wrestling performance of my brother and his teammates for their first meet. It was my first time ever watching wrestling but I was overflowing with a wrestlers passion. By that night, I already knew I wanted to join the (insert school here) wrestling team, assuming I would be granted acceptance into (insert school here). Two years later, I was in the same position as my brother, ebulliently awaiting my time to shine and live up to my brothers undefeated novice record. Unfortunately, my enthusiasm was put to rest after tragically experiencing countless defeats. The entire season was quite disheartening. I finished off with only three wins and six losses but never once thought of dropping out of the team next season. I did, however give up all my wrestling ambitions and resolved to be less competitive next season. Fortunately, things soon started to take a turn for the better. Sophomore year arrived faster than I thought it would and before I knew it, a few months had passed and wrestling season was going strong. Our first competition was a tournament and my coach entrusted me to wrestle four matches. I was losing all of what little confidence I had while I was warming up, as usual, before my first match. Lastly, I comforted myself by thinking that losing does not matter, ran out on the mat, and let instinct take care of the rest. To my amazement, by the time the blood had rushed back to my head, I was standing in the center of the mat with my hand raised. Being a very objective person, just one win was all my ego needed to believe in myself again. I won all four matches that day and felt like a new person, ready to take on any challenge. The whole season was one of the most enjoyable portions of my life, packed with thrill and passion for the sport. I finished with twenty-four wins and seven losses. I worked hard all season, never forgetting the path I took, and was rewarded with a new sense of pride. Someone might think my trophy is a physical symbol of the honor I earned during my successful, but, in truth, it is an icon of my failure.