ОПРЕДЕЛЕНИЕ РАЗМЕРОВ МОЛЕКУЛЫ ОЛЕИНОВОЙ КИСЛОТЫText 1:The extinction of many species of birds has undoubtedly been hastened by modern man; since 1600 it has been estimated that approximately 100 bird species have become extinct over the world. In North America, the first species known to be annihilated was the great auk, a flightless bird that served as an easy source of food and bait for Atlantic fishermen through the beginning of the nineteenth century. Shortly after the great auk's extinction, two other North American species, the Carolina parakeet and the passenger pigeon, began dwindling noticeably in numbers. The last Carolina parakeet and the last passenger pigeon in captivity both died in September 1914. In addition to these extinct species, several others such as the bald eagle, the peregrine falcon, and the California condor are today recognized as endangered; steps are being taken to prevent their extinction. 1. The number of bird species that have become extinct in the United States since 1600 most probably is: a) more than 100; b) exactly 100; c) less than 100; d) exactly three. 2. The passage implies that the great auk disappeared: a) before 1600; b) in the 1600's; c) in the l800's; d) in the last fifty years. 3. It can be inferred from the passage that the great auk was killed because: a) it was eating the fishermen's catch; b) fishermen wanted to eat it; c) it flew over fishing areas; d) it baited fishermen. 4. The paragraph following this passage most probably discusses: a) what is being done to save endangered birds; b) what the bald eagle symbolizes to Americans; c) how several bird species became endangered; d) other extinct species. Text 2: Checks and balances are an important concept in the formation of the U.S. system of government as presented in the Constitution of the United States. Under this conception of government, each branch of government has built-in checks and limitations placed on it by one or more different branches of government in order to ensure that any one branch is not able to usurp total dominance over the government. Under the Constitution, the United States has a tripartite government, with power divided equally among the branches: the presidency, the legislature, and the judiciary. Each branch is given some authority over the other two branches to balance the power among the three branches. An example of these checks and balances is seen in the steps needed to pass a law. Congress can pass a law with a simple majority, but the president can veto such a law. Congress can then counteract the veto with a two-thirds majority. However, even if Congress passes a law with a simple majority or overrides a presidential veto, the Supreme Court can still declare the law unconstitutional if it finds that the law is contradictory to the guidelines presented in the Constitution. 5. The expression "dominance over" in line 3 is closest in meaning to: a) understanding of; b) dispute over; c) authority over; d) rejection of. 6. The word "tripartite" in line 4 suggests that something is: a) divided into three; b) totally democratic; c) powerfully constructed; d) evenly matched. 7. The "judiciary" in line 5 is: a) the electorate; b) the authority; c) the legal system; d) the government. 8. The word "counteract" in line 8 is closest in meaning to: a) vote for; b) debate; c) surpass; d) work against. 9. "Contradictory to" in line 10 is closest in meaning to: a) in agreement with; b) opposite to; c) supported by; d) similar to. Text 3:The American flag is the end product of a long evolution. Each of its component parts has its own history. The very first American flag washoisted in the skies over Boston on January 1, 1776, by the American forces there. This first flag consisted of thirteen red and white stripes representing the number of American colonies. It also included the British Cross of St. George and Cross of St. Andrew. It could be considered rather ironic that these symbols of British rule were included, on the American flag in that the American colonists were fighting for independence from the British. The origin of the stars on the current flag is obscure; that is, the stars could possibly have been taken from the flag of Rhode Island, or they could have been taken from the coat-of-arms of the Washington family. According to legend, this first flag with stars was sewn by Betsy Ross, a Philadelphia seamstress who was famous for her clever needlework. This version of the flag contained thirteen stars and thirteen stripes, one for each of the thirteen colonies battling for independence. The original idea was to add one star and one stripe for each state that joined the new, young country. However, by 1818, the number of states had grown to twenty, and it did not work well to keep adding stripes to the flag. As a result, Congress made the decision to revert to the original thirteen stripes representing the thirteen original colonies and adding a star each time a new state was admitted. This has been the policy ever since. 10. In line 8, the word "seamstress" is used to describe someone who: a) works at home; b) sews; c) is a part of high society; d) practices medicine. 11. The word "work" in line 12 could best be replaced by: а) get a job; b) function; c) accomplish; d) make an effort. 12. The word "keep" in line 12 could best be replaced by: a) continue; b) maintain; c) hold; d) guard. 13. The expression "revert to" in line 12 means: a) return to; b) add to; c) rejoice over; d) forget about. 14. The word "product" in line 1 is closest in meaning to: a) goods; b) merchandise; c) banner; d) result. 15. Something that is "hoisted" (line 2) is: a) created; b) found; c) raised; d) made. 16. The word "ironic" in line 3 could most easily be replaced by: a) steellike; b) normal; c) unexpected; d) nationalistic. 17. Which of the following is closest in meaning to "obscure" in line 6? a) Unclear; b) original; c) modern; d) known. Text 4:The rattlesnake has a reputation as a dangerous and deadly snake with a fierce hatred for humanity. Although the rattlesnake is indeed a venomous snake capable of killing a human, its nature has perhaps been somewhat exaggerated in myth and folklore. The rattlesnake is not inherently aggressive and generally strikes only when it has been put on the defensive. In its defensive posture the rattlesnake raises the front part of its body off the ground and assumes an S-shaped form in preparation for a lunge forward. At the end of a forward thrust, the rattlesnake pushes its fangs into the victim, thereby injecting its venom. There are more than 30 species of rattlesnakes, varying in length from $10 inches to 6 feet and also varying in toxicity of venom. In the United States there are only a few deaths annually from rattlesnakes, with a mortality rate of 'less than 2 per cent of those attacked. 18. Which of the following would be the best title for this passage? a) The Exaggerated Reputation of the Rattlesnake; b) The Dangerous and Deadly Rattlesnake; c) The Venomous Killer of Humans; d) Myth and Folklore about Killers. 19. According to the passage, which of the following is true about rattlesnakes? a) They are always ready to attack; b) they are always dangerous and deadly; c) their fierce nature has been underplayed in myth and folklore; d) their poison can kill people. 20. The word "posture" in line 5 is closest in meaning to which of the following? a) Mood; b) fight; c) position; d) strike. 21. When a rattlesnake is ready to defend itself it: a) lies in an S-shape on the ground; b) lunges with the back part of its body; c) is partially off the ground; d) assumes it is prepared by thrusting its fangs into the ground. 22. It can be inferred from the passage that: a) all rattlesnake bites are fatal; b) all rattlesnake bites are not equally harmful; c) the few deaths from rattlesnake bites are from six-foot snakes; d) deaths from rattlesnake bites have been steadily increasing. 23. The word "mortality" in line 10 is closest in meaning to: a) percentage; b) illness; c) death; d) survival. 24. The author's purpose in this passage is to: a) warn readers about the extreme danger from rattlesnakes; b) explain a misconception about rattlesnakes; c) describe a rattlesnake attack; d) clarify how rattlesnakes kill humans. Text 5:A hoax, unlike an honest error, is a deliberately concocted plan to present an untruth as the truth. It can take the form of a fraud, a fake, a swindle, or a forgery, and can be accomplished in almost any field: successful hoaxes have been foisted on the public in fields as varied as politics, religion, science, art, and literature. A famous scientific hoax occurred in 1912 when Charles Dawson claimed to have uncovered a human skull and jawbone on the Piltdown Common in southern England. These human remains were said to be more than 500,000 years old and were unlike any other remains from that period; as such they represented an important discovery in the study of human evolution. These remains, popularly known as the Piltdown Man and scientifically named Eoanthropus dawsoni after their discoverer, confounded scientists for more than forty years. Finally in 1953, a chemical analysis was used to date the bones, and it was found that the bones were modern bones that had been skill fully aged. A further twist to the hoax was that the skull belonged to a human and the jaws to an orangutan. 25. The topic of this passage could best be described as: a) the Piltdown Man; b) Charles Dawson's discovery; c) Eoanthropus dawsoni; d) a definition and example of a hoax. 26. The author's main point is that: a) various types of hoaxes have been perpetrated; b) Charles Dawson discovered a human skull and jawbone; c) Charles Dawson was not an honest man; d) the human skull and jawbone were extremely old. 27. The second paragraph includes: a) an illustration to support the ideas in the first paragraph; b) a counterargument to the ideas in the first paragraph; c) an analogy to the ideas in the first paragraph; d) a detailed definition of a hoax. 28. The word "concocted" in line 1 most probably means: a) issued; b) spoken; c) implemented; d) fabricated. 29. The word "confounded" in line 8 is closest in meaning to: a) confused; b) prevented; c) determined; d) discovered. 30. The passage does NOT mention about hoaxes in the field of: a) creating works of art; b) athletic events; c) writing books; d) research work.
ВИЗНАЧЕННЯ РІВНЯ МОВЛЕННЄВОЇ КОМПЕТЕНЦІЇ (11 клас) Directions: Select three tasks from those before you. After selecting three, choose one you are most capable to speak on and return the other two. Take about a minute to collect your thoughts before you begin to speak on the topic.
• Why do you feel this event happened the way it did? • Explain any mistakes people made in this event. • How would you have done things differently? 2) You need to call up customer service for your new computer; it has some things going wrong with it. • Explain the problem to the customer service representative. • Tell the representative what you have already done to try to fix the problem. • Explain to the representative why you feel you deserve a refund for your computer. 3) You have an.opportunity to create your own island nation in the South Pacific Ocean. • What type of government would it have (who would be in charge, how would they be chosen)? • What laws would you pass first to protect your government and its people? • What rights do you consider most important for your country? 4) You have just been appointed head of public relations for all of Ukraine. It's your job to encourage tourism in this country. • What aspects of life or places in Ukraine do you consider to be the most important for foreign tourists? • You have the chance to change one thing for Ukraine. What would you change that would make the country more enjoyable for tourists? • Think of a motto for Ukraine's tourism industry. 5) What do you believe to be the greatest problem in today's society? • Describe where you see it. • Explain why you consider it to be so bad; how does it affect society as a whole and the individuals making up that society? • How would you propose to do away with this problem? 6) You are about to be alone for ten years of your life, most likely on a desert island where you will only be able to work on your tan and not do much else. What two books (fiction or otherwise) would you bring with you, knowing they would be all you could read for ten years, and explain why. • What one musical piece would you bring to listen to (a band or a specific piece of music)? Explain why. • What one meal would you bring with you to enjoy for every night of those ten years? Explain why. 7) You are about to run for election for a major governmental office. • What do you consider to be your most important campaign issue? • What laws do you think need to be passed in order to make the issue you chose most acceptable? • What will the opposition say to your campaign, and how will you argue against them? 8) You are consulted to help compile a list of the best books written in the past century. • What three books would you want to put on this list? • What is it that makes these three books so great? • Explain whether, and how, these books affected literature that came after it. 9) What is more important: fame and money, or goodness of character? • Explain your point of view, and what you define as «good character». • Use examples of real people to describe people who have followed either fame and money, or pursued a strong character. • How do people normally act? Do they aim for moral character or for money? Why? Is it impossible to have both? 10) A close friend of yours is making an important decision that you feel is going to be a mistake. • Explain to your friend why you feel that decision is a mistake. • Try to tell him/her something else to do that would be a better decision. • Explain what will happen if he/she chooses still to make the original decision, and tell whether you will support him/her anyway. 11) You are at a party with a loud foreign visitor who is complaining about Ukraine. According to this person, his/her country is a better place. • Defend your country, telling this visitor the positive points of Ukraine. • Name one or two things that are already improving for Ukraine. • Suggest things that this foreigner could do to improve his/her opinion of Ukraine.
• How will you explain your situation to your boss? • Your boss does not want to let you go; he/she says that you need to be at work that night. What do you do? • One of your co-workers offers to work for you if you work for her twice next week. Will you do it? 13) Your pen pal from the United States asks you how you think things have changed in Ukraine since independence. • What do you tell him/her in general? • What is the most positive change during this time? • What is the most negative change during this time? 14)You are going to start up a new business; you have money, you have the space, you have the workers. • What product will you sell? • What types of people would be interested in your product? • How will you advertise this product? Give a sample advertising motto. 15) Your neighborhood is becoming increasingly worried about its safety; someone in your block was recently robbed. • What do you suggest your neighbors should do in order to protect themselves? • How will you make sure that you are safe at all times? • One of your friends is visiting you, and decides to walk home; how do you convince him/her that they should go alone? 16) Do you believe in the proverb «When in Rome, do as the Romans do?» • Explain situations when it is important to follow this advice. • When is it important to ignore this advice? • When living in a different country, is it important to forget old customs in order to follow the local customs? 17) You are working on a committee considering at the possibility of Ukraine entering the European Union. • Do you think that it is important for Ukraine to enter the EU? • What benefits will Ukraine get when entering the EU? • What changes would Ukraine have to go through in order to enter the EU? 18) Think about female role-models in the world. • Who do you think is the most important female role-model in Ukraine? In the world? • What have these women done to improve life for women in the world? • How important do you think it is to have female role-models? What role do they play? 19) What stereotypes do you think foreigners have about Ukraine? • Do you feel that these stereotypes are correct? • What stereotypes do you feel are particularly harmful for the Ukrainian people? • What can you do to change these stereotypes? 20) Do you feel that history repeats itself? • What events can you think of that are examples of history repeating itself? • What events can you think of that have shown people learning from past mistakes and improving? • What can you do to avoid repeating past mistakes?
ТВОРЧА ПИСЬМОВА РОБОТА (11 КЛАС) 1. Nowadays young people often choose their future profession without cut out for it but just for the sake of expected financial benefit. 2. It is absolutely necessary that Ukraine reshape itself following the countries of the European Union. 3. It is unfair that Ukrainian higher education diplomas are not recognized in many developed countries.
ОПРЕДЕЛЕНИЕ РАЗМЕРОВ МОЛЕКУЛЫ ОЛЕИНОВОЙ КИСЛОТЫ
Цель работы: 1. Изучить метод определения размеров молекулы олеиновой кислоты при растекании раствора на поверхности воды. 2. Определить эффективный диаметр и длину молекулы олеиновой кислоты. Литература: 1. Д.В.Сивухин. Общий курс физики. Термодинамика и молекулярная физика. М., Наука, 1979, с.332-335, 426-429 2. А.Н.Матвеев. Молекулярная физика. М., Высшая школа, 1981, с.278-285. 3. И.В.Савельев. Курс общей физики. том.1. М., Наука, 1987 с.371-382.
ТЕОРИЯ
Внутреннее строение жидкостей сложнее строения газов. Во-первых, мы считаем в газах молекулы свободными, движущимися независимо друг от друга, если только не считать их случайных столкновений между собой. В жидкостях молекулы настолько сближены, что столкновения между ними должны происходить несравненно чаще, чем в газах. Вследствие этого каждая молекула должна двигаться около некоторого среднего своего положения, меняющегося сравнительно медленно, т.е. постепенное перемещение молекул с одного места на другое в жидкостях происходит в течение большего промежутка времени, чем в газах. Во-вторых, поскольку межмолекулярные промежутки в жидкостях невелики, то пренебрегать силами взаимодействия молекул нельзя. Эти силы называют силами сцепления и их величина уменьшается в зависимости от расстояния значительно быстрее, чем у силы гравитационного взаимодействия. Конечно, силы сцепления имеются и в газах, но они весьма малы и поэтому большой роли не играют. В жидкостях же, наоборот, наличие этих сил постоянно обнаруживается во множестве разнообразных явлений и притом в особенности вблизи их поверхности. Когда молекула А (рис.1) находится внутри жидкости, то она со всех сторон окружена такими же молекулами, действующими на нее с силами сцепления, радиус действия которых ограничен расстоянием, обозначим его R. На эту молекулу практически не действуют те молекулы, которые находятся в н е сферы радиуса R, а силы взаимодействия внутренних молекул (по причине их симметричного и равномерного расположения) на молекулу А компенсируются. На рис 1. изображены плоскости а,б,в,г,д,е,ж,з,и,к - расстояния между которыми равны радиусу сферы частичного взаимодействия молекул R.
Когда молекула 2 находится на поверхности (воображаемой) жидкости, то равномерность распределения молекул внутри сферы частичного взаимодействия нарушается (вне жидкости - газ, и число молекул в единице объема в миллионы раз меньше, чем в жидкости) и равнодействующая сил сцепления направлена внутрь жидкости перпендикулярно ее поверхности, молекула как бы втягивается внутрь жидкости силой, удерживающей ее от вылета из жидкости. Это относится не только ко всем молекулам, находящимся у поверхности жидкости, но и к тем, которые находятся внутри жидкости на расстоянии от ее поверхности, меньшем радиуса R. Плоскость "е" является нижней границей поверхностной пленки, частицы которой подвержены действию сил, направленных внутрь жидкости. Вся эта пленка оказывает давление на жидкость, которое похоже на давление надутого резинового шарика на находящийся в нем воздух. Однако такое сравнение верно только внешне. Различие состоит в том, что при увеличении площади поверхности резиновой пленки увеличивается расстояние между молекулами и сама длина молекул (они "тянутся"), при растяжении же поверхности жидкости увеличивается число ее молекул в единице площади, т.е. в "пустые" места перемещаются молекулы из глубин жидкости. Математически это выражается в том, что сила натяжения резины, по сути сила упругости, в соответствии с законом Гука зависит от величины деформации и при равенстве сил упругости и внешней силы, вызвавшей деформацию, наступает состояние равновесия (шар больше не увеличивается в объеме). В случае же поверхностного натяжения величина натяжения не зависит от площади поверхности пленки, по крайней мере до тех пор, пока толщина пленки не становится весьма малой (как показывают измерения - порядка 5·10- 4 м). Fпов = s·l,
где s- некоторая постоянная величина, характеризующая вещество пленки (она называется поверхностным натяжением); l - длина линии, перпендикулярно которой действует сила поверхностного натяжения.
На рис.2 изображена поверхность жидкости у края капилляра (твердое тело) в случае смачивающей жидкости, а на рис.3 - несмачивающая жидкость. Сила R-равнодействующая всех сил, действующих на элемент (частицу) жидкости, q-краевой угол. В случае смачивающей жидкости силы сцепления молекул жидкости с молекулами твердого тела больше, чем между молекулами жидкости. Сила R всегда направлена перпендикулярно касательной к поверхности жидкости, т.к. только при этом условии поверхность жидкости будет в покое.
На рис.4 представлена в сечении часть капли смачивающей жидкости на поверхности твердого тела (трехфазная система).Форма капли определяется влиянием сил взаимодействия молекул трех сред: газа (1), жидкости (2) и твердого тела (3).
Эти три среды имеют общую границу (рис.5), внутри которой содержится элемент m вещества (заштрихованный диск). На внешнюю поверхность диска кроме обычного давления, одинакового со всех сторон, действуют еще силы поверхностного натяжения h·s13, h·s12, h·s23, где h длина дуги окружности диска,расположенной внутри каждой поверхностной пленки. Эти силы будут направлены перпендикулярно к отдельным элементам окружности и по касательным к соответствующим поверхностям раздела. Обозначим через q угол между поверхностью жидкость – газ и поверхностью твердого тела. Одним из условий равновесия диска является равенство нулю векторной суммы действующих на него сил. В случае, когда можно пренебречь силой тяжести по сравнению с силами поверхностного натяжения, имеем: s12·cosq - s13 + s23 = 0, откуда: s23 - s13
s12
Так как s12, s13, s23 постоянны, а cosq не может быть больше 1, то в случае равновесия имеет место условие
s23 - s13 -------------- = < 1. s12
Угол q, определяемый равенством (1), называют краевым углом. Каждая комбинация твердого, жидкого и газообразного тела характеризуется определенным краевым углом. Если
s23 - s13 > 0,
то угол q острый. В этом случае говорят, что имеет место частичное смачивание. Если s23 - s13 < 0,
то cos q > 0 и угол q - тупой, имеет место частичное несмачивание. Примерами полного смачивания являются соприкосновение со стеклом этилового и метилового спиртов и бензина. Частично смачивают стекло, например, эфир (q = 160) и керосин (q = 260). Многие органические жидкости (эфир, скипидар, керосин) растекаются по поверхности воды, т.е. имеет место полное смачивание. Для некоторых жидкостей (бензол, жирные кислоты, масло) явление максимального растекания наблюдается только для первых капель, помещенных на поверхность чистой воды. Это объясняется загрязнением поверхности воды первыми каплями при их растекании и как следствие этого - уменьшением поверхностного натяжения настолько, что равновесие капель становится возможным. Если площадь поверхности воды достаточно велика, то может образоваться мономолекулярный слой, т.е. слой толщиной в одну молекулу. Расположение таких молекул на поверхности воды показано на рис.6.
В настоящей работе для определения размеров молекул олеиновой кислоты используется метод, предложенный Ленгмюром и Дево. Для измерений используется кювета 60 см Х 40 см. Когда капля раствора олеиновой кислоты в легколетучей жидкости (спирте) падает на поверхность воды, то растворитель быстро испаряется, а олеиновая кислота растекаясь, образует на поверхности воды мономолекулярный слой (при достаточной для этого поверхности чистой воды). Если поверхность воды посыпать предварительно тонким слоем пробковых опилок или талька, то на ней образуется свободное от порошка округлое пятно. По диаметру этого пятна можно приближенно рассчитать площадь поперечного сечения одной молекулы олеиновой кислоты. Если в капле раствора содержится n молекул олеиновой кислоты, каждая с площадью поперечного сечения Sm, то
Sm·n = S (2),
где S - площадь круга, образованного растекшейся олеиновой кислотой на поверхности воды. Из (2) имеем:
Число молекул олеиновой кислоты n в капле можно найти, если известны масса m олеиновой кислоты, содержащаяся в капле раствора, и ее молярная масса М:
n = m·Na/M (4),
где Na - число Авогадро. Тогда эффективный диаметр одной молекулы d находим по формуле:
Длину h молекулы олеиновой кислоты грубо можно оценить, руководствуясь следующими соображениями:
h = V/S (6),
где V - объем мономолекулярного слоя, S - площадь его поверхности (площадь круга, диаметр которого Dср).
V = m/r
где m - масса олеиновой кислоты в капле раствора, r - плотность олеиновой кислоты. Подставив выражения S и V в (6), получим:
|
cosq = --------------- (1).
(3).
(5).
(7)
