Law of Constant Composition in Chemistry

In chemistry, the law of constant composition (also known as the law of definite proportions) states that samples of a pure compound always contain the same elements in the same mass proportion. This law, together with the law of multiple proportions, is the basis for stoichiometry in chemistry. In other words, no matter how a compound is obtained or prepared, it will always contain the same elements in the same mass proportion. For example, carbon dioxide (CO2) always contains carbon and oxygen in a 3:8 mass ratio. Water (H2O) always consists of hydrogen and oxygen in a 1:9 mass ratio. Law of Constant Composition History Discovery of this law is credited to the French chemist Joseph Proust, who through a series of experiments conducted from 1798 to 1804 concluded that chemical compounds consisted of a specific composition. Considering John Daltons atomic theory was only just beginning to explain that each element consisted of one type of atom and at the time, most scientists still believed elements could combine in any proportion, Prousts deductions were exceptional. Law of Constant Composition Example When you work with chemistry problems using this law, your goal is to look for the closest mass ratio between the elements. Its okay if the percentage is a few hundredths off. If youre using experimental data, the variation might be even greater. For example, lets say that using the law of constant composition, you want to demonstrate that two samples of cupric oxide abide by the law. Your first sample was 1.375 g cupric oxide, which was heated with hydrogen to yield 1.098 g of copper. For the second sample, 1.179 g of copper was dissolved in nitric acid to produce copper nitrate, which was subsequently burned to produce 1.476 g of cupric oxide. To work the problem, youd need to find the mass percent of each element in each sample. It doesnt matter whether you choose to find the percentage of copper or the percentage of oxygen. Youd simply subtract one of the values from 100 to get the percent of the other element. Write down what you know: In the first sample: copper oxide 1.375 gcopper 1.098 goxygen 1.375 - 1.098 0.277 g percent oxygen in CuO (0.277)(100%)/1.375 20.15% For the second sample: copper 1.179 gcopper oxide 1.476 goxygen 1.476 - 1.179 0.297 g percent oxygen in CuO (0.297)(100%)/1.476 20.12% The samples follow the law of constant composition, allowing for significant figures and experimental error. Exceptions to the Law of Constant Composition As it turns out, there are exceptions to this rule. There are some non-stoichiometric compounds that exhibit a variable composition from one sample to another. An example is wustite, a type of iron oxide that may contain 0.83 to 0.95 iron per each oxygen. Also, because there are different isotopes of atoms, even a normal stoichiometric compound may display variations in mass composition, depending which isotope of the atoms is present. Typically, this difference is relatively small, yet it does exist and can be important. The mass proportion of heavy water as compared with regular water is an example.

Analysis Of Homer s Odyssey - 1710 Words

Dvir Reif Classics 28 Professor Griffith 4 March 2016 Odysseus’ Divide Homer’s Odyssey provides a detailed account of the Greek hero Odysseus’ return home after the end of the Trojan War and the many obstacles and adventures he encounters along his journey. Depicting a non-traditional heroic character, this epic poem gives an insight into the intricate relationships between mortals and gods, commenting as well on societal norms and expectations in ancient Greece. Odysseus, though not developing as a character in Homer’s Odyssey, experiences dynamic shifts in his character throughout the poem. This constant shifting between two contrasting versions of his character allows Odysseus to be situated as a representation of mankind, a fusion of both civilization and barbarism. Odysseus exhibits an initially civilized attitude upon meeting the Cyclops Polyphemos. Odysseus does not realize, as he explains to the Phaiakians later on, that he â€Å"would encounter a man who was endowed with great strength, and wild, wi th no true knowledge of laws or any good customs†(IX. 214-215), and acts accordingly. This whole interaction between Odysseus and Polyphemos represents a perversion of the guest-friendship relationship that is highly emphasized throughout the Odyssey. The guest-friendship relationship with the Phaiakians provides a basis of comparison for this interaction. Their overall generosity and willingness to help Odysseus, is completely reversed in the situation with the Cyclops.Show MoreRelatedAnalysis Of Homer s Odyssey By Homer1202 Words   |  5 Pagescoping with the idea of losing his father and letting others to rule Ithaca. It is noticeable from the beginning of The Odyssey, written by Homer that Telemachus finds himself in a complicated situation where his life is seen to be in danger. He is a character of being distance from people. The idea of Telemachus becoming his own father, threatens suitor’s control in Ithaca. Homer describes Telemachus as a teenager who has not found himself and is on a mission to become an adult as his father. TelemachusRead MoreAnalysis Of Homer s Odyssey By Homer1095 Words   |  5 Pagesused in Homer’s Odyssey is the digression. The digression is departure from the main storyline that does not alter the action of the story, but adds a layer of sentimental content to the plot which usually helps underscore themes central to the story. The digressions in the Odyssey are meticulously written with great attention to detail just like the rest of the epic, and they truly help readers grasp the important aspects of the story. The liberal use of digression in the Odyssey helps build a vividRead MoreAnalysis Of Homer s Odyssey By Homer2018 Words   |  9 PagesThe Odyssey by Homer is more light in tone than the Iliad, of the same author: The good wins while the evil is punished. Even though the gods are still strict, the relationship between Odysseus and Athena is a more sincere and equal a relationship than between G od and Man in the Iliad. Odysseus is distinguished not only by his bravery, but largely by his intellect and cunning. He is the type of resourceful man whom never gives up, thinks of the causes, is reverent and never gives in. The Odyssey isRead MoreAnalysis Of Homer s Odyssey, By Homer915 Words   |  4 PagesThroughout the Odyssey, the hero, Odysseus is portrayed in two different and contradicting lights: the wise hero and the capricious leader blinded by his own pride. The epic writer, Homer, embodies the theme of hubris throughout Odysseus’ journey home. The idea of hubris, a trait of excessive pride, significantly develops personalities of characters within The Odyssey, and Homer ultimately creates a statement about excessive pride. The dual portrayal of Odysseus leads the reader to ultimatelyRead MoreAnalysis Of Homer s Odyssey By Homer Essay1479 Words   |  6 Pages The word â€Å"Family†, according to Merriam Webster, is thought to be a group of people brought together by common affiliation. The same cannot be said for the culture in the Odyssey by Homer. In the Odyssey, Odysseus is trying to get back home from fighting in the Trojan War. He has been away from home for almost 20 years longing to just be reunited with his kinfolk. Along the way, he comes across many obstacles that hinders him from reaching his home and family in in Ithaca. Luckily, the memoriesRead MoreAnalysis Of Odyssey By Homer s Odyssey2253 Words   |  10 Pagesand Midwifery Council, 2006). The literature surrounding the subject of mentorship is vast and fails to provide a single definition, however the terms used are often similar. Colley (2000) writes that the word mentor originated in Homer’s poem ‘Odyssey’ in which the character oversees the development of Telemachus. Usually mentoring describes the process of an experienced team member using their skills and knowledge to educate and develop a junior or less skilled co-worker (Chartered Institute ofRead MoreAnalysis Of Homer s The Odyssey 1483 Words   |  6 PagesViolence in The Odyssey Violence in Literature can take any form, whether it be natural disaster like and earthquake or a human based disaster like war (Campbell). In Homer’s The Odyssey both types are found†¦ whether it’s Odysseus’s hardships like making it home or dealing with the wrath of the god Poseidon. Every violent scene has its own reasons, some are more reasonable than others. For instance, the gods were angered by the disobedience of the mortals, this is more reasonable than the killingRead MoreAnalysis Of Homer s The Odyssey 795 Words   |  4 Pages Odysseus Epic Hero In the Epic, â€Å"The Odyssey, spoken by Homer, conveys a heroic tale of an epic hero named, Odysseus, who faces many challenges as he sails to get home. One of the tasks Odysseus faces is, The Sirens, who challenge Odysseus s will power. Another challenge Odysseus encounters is, â€Å"The Cyclops, who torments and slaughters some of Odysseus s men due to his curiosity. One of the hardest threats he had to confront was, â€Å"The Land ofRead MoreAnalysis Of Homer s The Odyssey1636 Words   |  7 PagesGreek society, Homer’s The Odyssey provides a detailed insight into the values of this intricate culture. In particular, this epic discusses the ways in which the deathless gods influence the fates of the mortals. The overall impact of the gods’ power is the mental straining that emerges from the unrelenting conflict of man versus immortal. Likewise, the actions and misfortunes of others also catalyze this extremely significant and powerful mental battle. Homerâ€⠄¢s The Odyssey reveals the values of ancientRead MoreAnalysis Of Homer s The Odyssey 1128 Words   |  5 Pages The Odyssey shows a lot of different stereotypes for women throughout the book, taking action to get what they want. Odysseus is trying to get back home after ten long years since the fall of troy, and his son is going out to find him. Throughout the book Odysseus meets lots of woman who vary in personality. He meets woman with the stereotypes: â€Å"mantis†- dominant, eats its mate, destroys to gain power, feared by many. â€Å"Damsel in distress†- persecuted maiden, woman placed in a dire predicament requires

EHT Task Free Essays

Guided Practice: a. Teacher follows the above procedure for each student working with each student both directly and indirectly. Teacher and aid will use both physical and verbal cues until student is able to work in pairs and then independently. We will write a custom essay sample on EHT Task or any similar topic only for you Order Now E. Independent Student Practice: a. Teacher will begin pairing students together based on ability to follow through with â€Å"kick the ball†. B. Students will be monitored for safety implicate, sharing and taking turns as well as using correct technique. C. Students who are non-compliant with safety procedures will work independently with teacher or aid as they kick the ball and retrieve it. D. Wheel chair students will receive moral and physical support as required. F. Culminating or Closing Procedure/Activity/Event: a. Students will participate in a non-traditional game of kick the ball; students will utilize a three base plus home plate field (set up like baseball). Each student will receive a turn to kick the ball and maneuver the basses. Students enable to walk or run or who are in a wheelchair will be assisted around the course. Students will receive instruction, praise and reward for all efforts and achievements. Pedagogical Strategy (or Strategies): Teacher will be utilizing direct instruction, one-on-one instruction, small group instruction and independent teaching strategies. Differentiated Instruction: Accommodations have been implemented for physically challenged students. Small group Para-pro for student with CUP. Classroom aid for wheelchair bound student and additional coverage where needed throughout the lesson. Technology Integration: Technology deemed inappropriate for this lesson format as physical exercise is required. Student Assessment/Rubrics: Assessment: Per state guidelines students are only required to participate so attendance will be taken and submitted. An alternative assessment could be documented and kept in student records and could be in the format of a rubric. Students could be measured as: Mastered, independent, guided, and physically assisted. This information could as well be kept in a teacher grade book used to monitor progress or regression. How to cite EHT Task, Papers