Answer - Unit 3 PDF [PDF]

Citation preview

UNIT 3 Physical Chemistry https://www.acs.org/content/acs/en/careers/college-to-career/areas-ofchemistry/physical-chemistry.html



What Is Physical Chemistry? Physical chemistry is the study of how matter behaves on a molecular and atomic level and how chemical reactions occur. Based on their analyses, physical chemists may develop new theories, such as how complex structures are formed. Physical chemists often work closely with materials scientists to research and develop potential uses for new materials. Physical chemistry has traditionally given students broad training, and positioned them to work in a variety of scientific careers. Many people trained as physical chemists ultimately work as analytical chemists, where they work to understand the fundamental process involved in analytical techniques, allowing them to enhance and expand those techniques. For example, Matt Lynch, senior scientist in the Beauty Care Division of Procter & Gamble, works in physical/analytical chemistry, conducting applied and basic surfactant research for product development applications. His work involves looking at the assembly of molecules and determining how to measure and quantify it. Lynch says, “We assemble molecules in crystals and solutions and look at how to measure that in terms of arrangements of atoms and molecules; how they grow to form bigger aggregates in solutions as well as in crystals; and how these aggregates of surfactants impart various properties to a product.” Lynch notes that he uses diffraction, infrared, and microscopy methods in his work. By developing better ways to measure and quantitate aspects of the ingredients, he helps his company develop better products. What Do Physical Chemists Do? Physical chemists are focused on understanding the physical properties of atoms and molecules, the way chemical reactions work, and what these



properties reveal. Their work involves analyzing materials, developing methods to test and characterize the properties of materials, developing theories about these properties, and discovering the potential use of the materials. Using sophisticated instrumentation and equipment has always been an important aspect of physical chemistry. Most physical chemistry labs are full of analytical instruments, which can include lasers, mass spectrometers, nuclear magnetic resonance, and electron microscopes. Physical chemists’ discoveries are based on understanding chemical properties and describing their behavior using theories of physics and mathematical computations. Physical chemists predict properties and reactions of chemicals, then test and refine those predications. They use mathematical analysis and statistics on huge datasets, sometimes with millions of data points, to reveal hidden information about compounds, materials, and processes. They may also conduct simulations, developing mathematical equations that predict how compounds will react over time. Recently, more and more physical chemists have found homes in the emerging fields of materials science and molecular modeling where their skills in analyzing and predicting the behavior of physical properties have exciting new applications. By combining the mathematical rigidity of physical chemistry with the practicality of new materials and new applications, the field of physical chemistry is expanding in new and exciting ways. Where Is Physical Chemistry Used? Physical chemists work in a variety of different areas, but their common goal is to discover, test, and understand the fundamental physical characteristics of a material — be it solid, liquid, or gas. Precision and attention to detail make their work somewhat similar to analytical chemistry, though physical chemists also stress the importance of applying knowledge of math and physics to develop a thorough understanding of the material.



Physical chemists generally have a strong curiosity about how things work at the atomic level and enjoy working with lab instrumentation and machines. Many are drawn to the fact that physical chemistry processes are similar to those of engineering, and many chemists enjoy using their knowledge and love of chemistry to make discoveries. A physical chemistry lab is characterized by the large machines and sophisticated instrumentation these scientists use to test and analyze materials. Many who work in the lab say their time is divided between working at the bench and working at their desks doing calculations and reviewing data. Physical chemists who go into management also spend time supervising other scientists, reviewing department needs and goals, and meeting with business managers in their companies. Examples of Chemistry in the Real World There are many examples of chemistry in daily life, showing how prevalent and important it is.   







Digestion relies on chemical reactions between food and acids and enzymes to break down molecules into nutrients the body can absorb and use. Soaps and detergents act as emulsifiers to surround dirt and grime so it can be washed away from clothing, dishes, and our bodies. Drugs work because of chemistry. The chemical compounds may fit into the binding site for natural chemicals in our body (e.g., block pain receptors) or may attack chemicals found in pathogens, but not human cells (e.g., antibiotics). Cooking is a chemical change that alters food to make it more palatable, kill dangerous microorganisms, and make it more digestible. The heat of cooking may denature proteins, promote chemical reactions between ingredients, carmelize sugars, etc.



The key concepts of physical chemistry are the ways in which pure physics is applied to chemical problems.



One of the key concepts in classical chemistry is that all chemical compounds can be described as groups of atoms bonded together and chemical reactions can be described as the making and breaking of those bonds. Predicting the properties of chemical compounds from a description of atoms and how they bond is one of the major goals of physical chemistry. To describe the atoms and bonds precisely, it is necessary to know both where the nuclei of the atoms are, and how electrons are distributed around them. [2] Quantum chemistry, a subfield of physical chemistry especially concerned with the application of quantum mechanics to chemical problems, provides tools to determine how strong and what shape bonds are, [2] how nuclei move, and how light can be absorbed or emitted by a chemical compound. [3] Spectroscopy is the related sub-discipline of physical chemistry which is specifically concerned with the interaction of electromagnetic radiation with matter. Another set of important questions in chemistry concerns what kind of reactions can happen spontaneously and which properties are possible for a given chemical mixture. This is studied in chemical thermodynamics, which sets limits on quantities like how far a reaction can proceed, or how much energy can be converted into work in an internal combustion engine, and which provides links between properties like the thermal expansion coefficient and rate of change of entropy with pressure for a gas or a liquid. [4] It can frequently be used to assess whether a reactor or engine design is feasible, or to check the validity of experimental data. To a limited extent, quasi-equilibrium and non-equilibrium thermodynamics can describe irreversible changes. [5] However, classical thermodynamics is mostly concerned with systems in equilibrium and reversible changes and not what actually does happen, or how fast, away from equilibrium. Which reactions do occur and how fast is the subject of chemical kinetics, another branch of physical chemistry. A key idea in chemical kinetics is that for reactants to react and form products, most chemical species must go through transition states which are higher in energy than either the



reactants or the products and serve as a barrier to reaction. [6] In general, the higher the barrier, the slower the reaction. A second is that most chemical reactions occur as a sequence of elementary reactions, [7] each with its own transition state. Key questions in kinetics include how the rate of reaction depends on temperature and on the concentrations of reactants and catalysts in the reaction mixture, as well as how catalysts and reaction conditions can be engineered to optimize the reaction rate.



A. Translate those paragraphs above into Bahasa Indonesia.



The fact that how fast reactions occur can often be specified with just a few concentrations and a temperature, instead of needing to know all the positions and speeds of every molecule in a mixture, is a special case of another key concept in physical chemistry, which is that to the extent an engineer needs to know, everything going on in a mixture of very large numbers (perhaps of the order of the Avogadro constant, 6 x 1023) of particles can often be described by just a few variables like pressure, temperature, and concentration. The precise reasons for this are described in statistical mechanics, [8] a specialty within physical chemistry which is also shared with physics. Statistical mechanics also provides ways to predict the properties we see in everyday life from molecular properties without relying on empirical correlations based on chemical similarities. [5]



Kimia fisika adalah ilmu yang mempelajari tentang bagaimana materi menunjukkan sifatnya pada tingkat molekuler dan atom dan bagaimana reaksi kimia terjadi. Berdasarkan analisis mereka, ahli kimia fisika dapat mengembangkan teori baru, seperti bagaimana struktur kompleks terbentuk. Ahli kimia fisika sering bekerja sama dengan ilmuwan bahan untuk meneliti dan mengembangkan potensi penggunaan bahan-bahan baru. Kimia fisika secara tradisional telah memberikan para siswa pelatihan yang luas, dan menempatkan mereka untuk bekerja dalam berbagai karir ilmiah. Banyak orang yang dilatih sebagai ahli kimia fisika akhirnya bekerja sebagai ahli kimia analitik, dimana mereka bekerja untuk memahami proses dasar yang terlibat dalam teknik analisis, yang memungkinkan mereka untuk meningkatkan dan memperluas teknik-teknik tersebut.



BAB 3 Kimia Fisika Apa itu Kimia Fisika?



Misalnya, Matt Lynch, ilmuwan senior di Divisi Perawatan Kecantikan Procter & Gamble, bekerja dalam bidang kimia fisika / analitik, melakukan riset surfaktan terapan dan dasar untuk aplikasi pengembangan produk. Karyanya menyangkut perakitan molekul dan menentukan bagaimana cara mengukur dan menghitungnya. Lynch mengatakan, “Kami menyusun molekul dalam kristal dan larutan dan melihat bagaimana mengukurnya dalam hal penyusunan atom dan molekul; bagaimana mereka tumbuh untuk membentuk agregat yang lebih besar dalam larutan maupun dalam kristal; dan bagaimana agregat surfaktan ini memberikan berbagai sifat pada suatu produk”. Lynch mencatat bahwa ia menggunakan metode difraksi, inframerah, dan mikroskopi dalam karyanya. Dengan mengembangkan cara yang lebih baik untuk mengukur dan mennghitung aspek-aspek dari penyusunnya, dia membantu perusahaannya mengembangkan produk yang lebih baik.



Apa yang Dilakukan Ahli Kimia Fisika? Ahli Kimia Fisika difokuskan pada pemahaman sifat fisik atom dan molekul, cara kerja reaksi kimia, dan apa saja sifat–sifat yang diperlihatkan. Pekerjaan mereka melibatkan analisis materi, mengembangkan metode untuk menguji dan mengkarakterisasi sifat-sifat bahan, mengembangkan teori tentang sifat-sifat ini, dan menemukan potensi penggunaan bahan. Menggunakan instrumen dan peralatan yang canggih selalu menjadi aspek penting dari kimia fisika. Kebanyakan laboratorium kimia fisika penuh dengan instrumen analitis, yang dapat mencakup laser, spektrometer massa, resonansi magnetik nuklir, dan mikroskop elektron. Penemuan ahli kimia fisika didasarkan pada pemahaman sifat kimia dan menggambarkan perilakunya menggunakan teori fisika dan perhitungan matematis. Ahli kimia fisika memprediksi sifat dan reaksi bahan kimia, kemudian menguji dan memilah predikasi tersebut. Mereka menggunakan analisis matematis dan statistik pada dataset besar, terkadang dengan jutaan titik data, untuk mengungkapkan informasi tersembunyi tentang senyawa, bahan, dan proses-proses. Mereka juga dapat melakukan simulasi, mengembangkan persamaan matematika yang memprediksi bagaimana senyawa akan bereaksi dari waktu ke waktu. Baru-baru ini, semakin banyak ahli kimia fisika menemukan “rumah” di bidang ilmu pengetahuan bahan dan pemodelan molekuler, dimana keterampilan mereka dalam menganalisis dan memprediksi perilaku dari sifat fisika memiliki aplikasi baru yang menarik. Dengan menggabungkan matematika kimia fisika yang kaku dengan kepraktisan bahan baru dan aplikasi baru, bidang kimia fisika berkembang dengan cara yang baru dan menarik. Dimana Kimia Fisika Digunakan? Ahli kimia fisika bekerja di berbagai bidang yang berbeda, tetapi tujuan bersama mereka adalah untuk menemukan, menguji, dan memahami karakteristik fisik mendasar dari suatu bahan — baik itu padat, cair, atau gas. Ketelitian dan perhatian terhadap detil membuat karya mereka agak



mirip dengan kimia analitik, meskipun ahli kimia fisika juga menekankan pentingnya menerapkan pengetahuan matematika dan fisika untuk mengembangkan pemahaman yang menyeluruh tentang bahan. Ahli Kimia Fisika umumnya memiliki keingintahuan yang kuat tentang bagaimana hal-hal bekerja pada tingkat atom dan menikmati bekerja dengan instrumentasi dan mesin laboratorium. Banyak yang tertarik pada fakta bahwa proses kimia fisika mirip dengan teknik, dan banyak ahli kimia menikmati menggunakan pengetahuan dan kecintaan mereka terhadap kimia untuk membuat penemuan. Sebuah laboratorium kimia fisika dicirikan oleh mesin-mesin besar dan instrumentasi canggih yang digunakan para ilmuwan untuk menguji dan menganalisis bahan-bahan. Banyak yang bekerja di lab mengatakan waktu mereka terbagi antara bekerja di bangku dan bekerja di meja mereka melakukan perhitungan dan meninjau data. Ahli kimia fisika yang masuk ke manajemen juga menghabiskan waktu mengawasi ilmuwan lain, meninjau kebutuhan dan sasaran departemen, dan bertemu dengan manajer bisnis di perusahaan mereka. Contoh-contoh Kimia di Dunia Nyata Ada banyak contoh kimia dalam kehidupan sehari-hari, yang menunjukkan betapa umumnya dan pentingnya hal itu.   



Pencernaan bergantung pada reaksi kimia antara makanan dan asam dan enzim untuk memecah molekul menjadi nutrisi yang dapat diserap dan digunakan tubuh. Sabun dan deterjen bertindak sebagai pengemulsi untuk memperangkap kotoran dan debu sehingga dapat dibersihkan dari pakaian, piring, dan tubuh kita. Obat-obatan berfungsi karena kimia. Senyawa kimia dapat masuk ke jaringan pengikat untuk bahan kimia alami dalam tubuh kita (misalnya, memblokir reseptor nyeri) atau dapat menyerang bahan kimia yang ditemukan pada patogen, tetapi bukan sel manusia (misalnya, antibiotik).







Memasak adalah perubahan kimia yang mengubah makanan agar lebih enak, membunuh mikroorganisme berbahaya, dan membuatnya lebih mudah dicerna. Panas memasak dapat mengubah sifat protein, meningkatkan reaksi kimia antara bahan-bahan, karamel gula, dan lainnya.



Konsep-konsep kunci kimia fisika adalah cara-cara dimana fisika murni diterapkan untuk masalah kimia. Salah satu konsep kunci dalam kimia klasik adalah bahwa semua senyawa kimia dapat digambarkan sebagai kelompok atom yang terikat bersama dan reaksi kimia dapat digambarkan sebagai pembentukkan dan pemutusan ikatan tersebut. Memprediksi sifat-sifat senyawa kimia dari deskripsi atom dan bagaimana ikatannya adalah salah satu tujuan utama kimia fisika. Untuk menggambarkan atom dan ikatan secara tepat, perlu diketahui baik dimana inti atom berada, dan bagaimana elektron didistribusikan di sekitar mereka. [2] Kimia kuantum, sebuah bagian bidang kimia fisika terutama yang berkaitan dengan penerapan mekanika kuantum untuk masalah kimia, menyediakan alat untuk menentukan seberapa kuat dan bentuk-bentuk ikatan, [2] bagaimana inti bergerak, dan bagaimana cahaya dapat diserap atau dipancarkan oleh senyawa kimia. [3] Spektroskopi adalah bagian disiplin ilmu kimia fisika yang terkait dengan interaksi radiasi elektromagnetik dengan materi. Serangkaian pertanyaan penting lainnya dalam kimia berkaitan dengan reaksi jenis apa yang dapat terjadi secara spontan dan sifat mana yang mungkin untuk campuran kimia tertentu. Ini dipelajari dalam termodinamika kimia, yang menetapkan batasan jumlah seperti seberapa jauh reaksi dapat dilanjutkan, atau berapa banyak energi yang dapat diubah menjadi kerja dalam mesin pembakaran internal, dan yang menyediakan hubungan antara sifat seperti koefisien ekspansi panas dan laju perubahan entropi dengan tekanan untuk gas atau cairan. [4] Ini sering dapat digunakan untuk menilai apakah desain reaktor atau mesin layak, atau



untuk memeriksa validitas data eksperimen. Secara terbatas, quasiequilibrium dan non-equilibrium termodinamika dapat menggambarkan perubahan yang tidak dapat diubah. [5] Namun, Termodinamika klasik sebagian besar berkaitan dengan sistem dalam keseimbangan dan perubahan reversibel (yang dapat kembali) dan bukan apa yang sebenarnya terjadi, atau seberapa cepat, jauh dari keseimbangan. Reaksi mana yang terjadi dan seberapa cepat subjek kinetika kimia, cabang kimia fisika lain. Sebuah ide kunci dalam kinetika kimia adalah bahwa untuk reaktan bereaksi dan membentuk produk, sebagian besar jenis kimia harus melalui keadaan transisi yang lebih tinggi dalam energi daripada reaktan atau produk dan berfungsi sebagai penghalang untuk bereaksi. [6] Secara umum, semakin tinggi penghalang, semakin lambat reaksinya. Yang kedua adalah bahwa sebagian besar reaksi kimia terjadi sebagai urutan reaksi elementer, [7] masing-masing memiliki keadaan transisi sendiri. Pertanyaan kunci dalam kinetika meliputi bagaimana laju reaksi tergantung pada suhu dan konsentrasi reaktan dan katalis dalam campuran reaksi, serta bagaimana katalis dan kondisi reaksi dapat direkayasa untuk mengoptimalkan laju reaksi. Fakta bahwa seberapa cepat reaksi terjadi sering dapat ditentukan hanya dengan beberapa konsentrasi dan suhu, daripada perlu mengetahui semua posisi dan kecepatan setiap molekul dalam campuran, adalah hal istimewa dari konsep kunci lain dalam kimia fisika, dimana bahwa sejauh seorang insinyur perlu tahu, segala sesuatu yang terjadi dalam campuran angka yang sangat besar (mungkin dari urutan konstanta Avogadro, 6 x 1023) partikel sering dapat digambarkan hanya dengan beberapa variabel seperti tekanan, suhu, dan konsentrasi. Alasan yang tepat untuk ini dijelaskan dalam mekanika statistik, [8] spesialisasi dalam kimia fisika yang juga dibagi dengan fisika. Mekanika statistik juga menyediakan cara untuk memprediksi sifat yang kita lihat dalam kehidupan sehari-hari dari sifat molekuler tanpa bergantung pada korelasi empiris berdasarkan persamaan kimia. [5]



B. Answer the following questions and discuss them :







1. Would you like to explain what is physical chemistry? Physical chemistry is the study of how matter behaves on a molecular and atomic level and how chemical reactions occur. 2. What do physical chemistry do? Physical chemists are focused on understanding the physical properties of atoms and molecules, the way chemical reactions work, and what these properties reveal. Their work involves : 



  



Analyzing materials, developing methods to test and characterize the properties of materials, developing theories about these properties, and discovering the potential use of the materials. Using analytical instruments, which can include lasers, mass spectrometers, nuclear magnetic resonance, and electron microscopes. Predict properties and reactions of chemicals, then test and refine those predications. Conduct simulations, developing mathematical equations that predict how compounds will react over time.



3. Where is physical chemistry used? Physical chemists work in a variety of different areas, but their common goal is to discover, test, and understand the fundamental physical characteristics of a material — be it solid, liquid, or gas. 4. Give some examples of physical chemistry in daily life ! 



Digestion relies on chemical reactions between food and acids and enzymes to break down molecules into nutrients the body can absorb and use.











Soaps and detergents act as emulsifiers to surround dirt and grime so it can be washed away from clothing, dishes, and our bodies. Drugs work because of chemistry. The chemical compounds may fit into the binding site for natural chemicals in our body (e.g., block pain receptors) or may attack chemicals found in pathogens, but not human cells (e.g., antibiotics). Cooking is a chemical change that alters food to make it more palatable, kill dangerous microorganisms, and make it more digestible. The heat of cooking may denature proteins, promote chemical reactions between ingredients, carmelize sugars, etc.



6. Mesopotamians used clay bricks in ziggurats at Uruk.



C. Focus on Grammar



7. Ancient Greeks built magnificent palaces and the huge complex of



Lesson 5 Prepositional Phrases



Knossos. 8. Greeks used masonry and decorated the walls of their structures with



A prepositional phrase begins with a preposition and ends with a noun or a pronoun called the object of the preposition. Some common prepositions are against, at, for, in, to, on, by, and with. A prepositional phrase can function as an adjective, modifying a noun or a pronoun. Darcy chose the bedroom above the garage. (Above the garage modifies the noun bedroom.) It may also function as an adverb when it modifies a verb, an adverb, or an adjective. That poem is meaningful to me. (To me modifies the adjective meaningful.)



frescoes. 9. Columns and beams were also among the Grecian trademarks. 10. Marble was widely used as a construction material during this classical period. 11. The Acropolis and the Parthenon are examples of the fine techniques of the Greeks. 12. The Romans later added their expertise to the Greek technology. 13. During the second century, Romans built structures made from concrete, terra cotta, and bricks.



Exercise 1 : Underline the prepositional phrase or phrases in each sentence. Architects design buildings and other structures for their clients. 1. Architecture is considered a form of art. 2. It is one of the oldest of the fine arts. 3. More is known about the structures of ancient times than about the builders. 4. Before the invention of construction equipment, architects relied on huge labor forces. 5. Examples of early architecture include the Egyptian pyramids and tombs of stone.



14. Architectural refinements by the Romans included the arch, the vault, and the dome. 15. Aqueducts, the Colosseum, and the Pantheon are examples of Roman structures. 16. Gothic architecture originated in Northern Europe. 17. The use of buttresses, arches, and vaults characterizes this style. 18. Gothic architecture is seen in many cathedrals in Paris. 19. Examples of Gothic architecture are found throughout Europe. 20. Many of the traditions of the past are reflected in modern architecture.



Exercise 2 : Draw one line under each prepositional phrase and two lines under the object of each preposition.



14. It is a series of structures with roofs of canvas and wood resting on



The name Frank Lloyd Wright is well known among architects.



15. The Guggenheim Museum in New York is another of Wright’s creations.



1. American architect Frank Lloyd Wright was a key figure in modern architecture. 2. Wright produced designs for residences and commercial buildings. 3. His designs are known for their originality. 4. With a style based on natural forms, Wright’s work is unique. 5. Though he studied civil engineering for a time, Wright worked in a design department. 6. On the side, Wright designed houses for clients of the firm. 7. The homes have low roofs and walls of windows. 8. Huge stone fireplaces are a central part of his home designs. 9. His commercial buildings have heavy walls with skylights for the primary light source. 10. At Robie House in Chicago, Wright blended the architecture with the surrounding landscape. 11. After 1893, Wright went out on his own. 12. He would become one of the most famous architects in the United States. 13. Taliesin West is a complex near Phoenix that became Wright’s home, workshop, and school.



walls of boulders.



16. It has a spiral design similar to the structure of seashells. 17. His designs are marked by the use of forms from nature. 18. One of his most famous buildings, Falling water, is located in a small town in Pennsylvania. 19. Cantilevers, or beams supported at one end, suspend the living room and terrace over a waterfall.



20. Falling water is now one of the most popular tourist attractions in Pennsylvania.



Lesson 6 Appositives and Appositive Phrases



8. Asthma, a disease of the respiratory system, is sometimes controllable with medication.



An appositive is a noun or a pronoun that further identifies another noun or pronoun.



9. The new boy in school, Derek Peterson, is from Montana.



My music teacher, Mr. Price, studied with famous musicians.



11. The chorus, a group made up of choir members, will perform tonight.



An appositive phrase is the appositive along with any modifiers. If not essential to the meaning of the sentence, it is set off by commas.



12. Beowulf, our assignment for English class, is about a hero of the middle



We rented bicycles to ride through that area, the most charming part of town.



13. That recliner, a lumpy old chair, is my uncle’s favorite.



Exercise 1 : Underline the appositive or appositive phrase in each sentence. Mr. Thompson, Dan’s father, works at a chemical plant.



10. My father, a former trumpet player, encouraged me to take lessons.



ages.



14. Our house, the two-story on the corner, is more than one hundred years old. 15. Her intelligence, a powerful asset, led her to a career in medicine. 16. Cindy and I always order the same dinner, a burrito and refried beans. 17. My neighbor Diane gives me a ride to school every morning.



1. Venus, the second planet from the sun, resembles Earth. 2. Some people prefer soft pretzels, large pretzels that are warmed, to ordinary pretzels. 3. My sister Pam marches in the band. 4. The rattlesnake, one of the most poisonous types of snake, is feared by many people. 5. My favorite comedians, Abbott and Costello, are in that movie. 6. The winner, the first runner to cross the finish line, will win a trophy. 7. My best friend Roberto is the treasurer of the Drama Club.



18. In chemistry we worked on a chemical solution, a combination of two acids. 19. Only Mother, a very patient person, can tolerate Tommy’s tantrums. 20. Davy Crockett, an American folk hero, was a pioneer who became a U.S. representative. 21. The teacher assigned a final project, a term paper. 22. Moussaka, a Greek dish, is my favorite food. 23. Every Friday after school we meet at the same place, the restaurant on the corner. 24. The test, a mixture of essay and multiple-choice questions, was easy.



25. Cairo, the capital of Egypt, has a hot, dry climate. 26. Janet’s uncle Jake is a teacher at the middle school. 27. That book, a mystery novel, is suspenseful. 28. Edison’s experiments led to an important discovery, the first central electric-light power station. 29. Samuel de Champlain, a French explorer, was the founder of Quebec. 30. The poet Robert Browning had an innovative style. 31. My cousin Tim came to watch me in the play. 32. Mr. Dixon, the new mayor, has been a politician for many years. 33. Daniel, our relief pitcher, finished the game. 34. Sarah is from Springfield, the capital of Illinois. 35. Mr. Ortega, our soccer coach, encourages us in our academic work. 36. Our favorite spot is Camp Lightfoot, a peaceful retreat. 37. Pegasus, a winged horse, is a mythical creature. 38. Lake Ontario, the smallest of the five Great Lakes, borders both Canada and New York. 39. The boy over there is Luis, the fullback of the football team. 40. Your breakfast, eggs and bacon, was easy to make. 41. Fans of baseball pitcher Orel Hershiser admire his longevity. 42. The artifact, an ornate bowl, was found in the desert. 43. Nathan became an Eagle Scout, the highest honor in scouting. 44. Our dog, a golden retriever, does many tricks.



45. The band concert, a series of songs by Gershwin, is scheduled for Tuesday. 46. Prince Edward Island, a popular vacation spot in Canada, is the setting for the TV series Anne of Green Gables. 47. Phoenix, the capital city of Arizona, lies in the Salt River Valley. 48. My friend Robert, the car expert, helped me choose new tires for my car.