...Using Freezing-Point Depression to Find Molecular Weight Wednesday, February 4, 2016 Tuan Nguyen Class: Tue-Thur: 11:00 am-12:20pm Abstract: The purposes of this experiment are: to determine the freezing point of water, solution (the water mixture), and use the information to determine the molar mass of the sucrose-water mixture. Calculate the error percentage will determine the accurate of the experiment. Introduction The experiment “ Using the Freezing Point to Determine the Molar Mass” focused on colligative properties. It’s based on the concentration of solute particles present and not the chemical identity of the solute. The colligative property is based on the idea that a solution freezes at a lower temperature than the pure solvent. Adding unknown impurities to a solution of water and studying the effects this solute “impurity” has on the freezing point can obtain valuable information about the identity of the substance. Experiment: The addition of a solute (sugar/ salt) to a solvent will decrease the freezing point (temperature) of the solvent. The decrease in freezing point, ∆ Tf, when a nonvolatile, nonionizing (non-dissociating) solute is dissolved in a solvent is proportional to the molality concentration, m, of the solute present in the solution. The partner used a copper wire to continue stir the water mixture (part B and C) with slight up-and-down motion for 10-minute duration of the experiment. To record the value of the freezing temperature...
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...Title: Colligative Properties Cathy Stone Western Governor’s University Reflection: Reflect on the important scientific practices (1) Constructing Explanations and (2) Using Mathematics, Information and Computer Technology, and Computational Thinking by doing the following: 1. Define each of the two scientific practices. Typically, students have the mentally that if they memorizes the facts for any subject area, they should be able to pass any class. However, that is not the case in most academic settings. There are two important scientific practices, (1) Constructing Explanations and (2) Using Mathematics, Information and Computer Technology, and Computational Thinking, that are critical for student success in a science...
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...Depression If you dissolve a substance such as ordinary table salt (NaCl) in water, the freezing point of the water will decrease relative to the freezing point of the pure water. This property is used to melt the snow or ice on roads during the winter or to make homemade ice cream. In this assignment, you will dissolve a sample of NaCl in water, add some ice, and then measure the freezing point depression. 1. Start Virtual ChemLab, select Colligative Properties, and select Freezing Point Depression from the list of assignments. The lab will open in the Calorimetry laboratory with a beaker containing 45.00 g of ice and a coffee cup calorimeter on the lab bench. A sample of sodium chloride (NaCl) will also be on the balance. 2. Click on the Lab Book to open it. Record the mass of the sodium chloride in the data table. If it is too small to read, click on the Balance area to zoom in, record the mass, and then return to the laboratory. 3. 100 mL of water is already in the calorimeter. Use the density of water at 25o C (0.998 g/mL) to determine the mass from the volume and record it in the data table. Make certain the stirrer is On (you should be able to see the shaft rotating). In the thermometer window, click Save to begin recording data in the lab book. Allow 20-30 seconds to obtain a baseline temperature of the water. Click the clock on the wall labeled Accelerate to accelerate the laboratory time if necessary. 4. Drag the...
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... 1. Start Virtual ChemLab, select Colligative Properties, and then select Heat of Fusion of Water from the list of assignments. The lab will open in the Calorimetry laboratory with a beaker of ice on the balance and a coffee cup calorimeter on the lab bench. 2. Click on the Lab Book to open it. Record the mass of the ice on the balance in the data table. If the mass is too small to read, click on the Balance area to zoom in. Note that the balance has already been tared for the mass of the empty beaker. 3. 100 mL of water is already in the coffee cup. Use the density of water at 25 C (0.998 g/mL) to determine the mass of water from the volume. Record the mass in the data table. Make certain the stirrer is On (you should be able to see the shaft rotating). In the thermometer window, click Save to begin recording data to the lab book. Allow 20-30 seconds to obtain a baseline temperature of the water. 4. Drag the beaker from the balance area until it snaps into place above the coffee cup and then pour the ice into the calorimeter. Click the thermometer and graph windows to bring them to the front and observe the change in temperature in the graph window until it reaches a minimum value and begins to warm again. Click Stop in the temperature window. (You can click on the clock on the wall labeled Accelerate to accelerate the time in the laboratory.) A data link icon will appear in the lab book. Click the data link icon and...
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...Boiling Point Elevation 4-4 Boiling Point Elevation If you dissolve a substance such as ordinary table salt (NaCl) in water, the boiling point of the water will increase relative to the boiling point of the pure water. In this assignment, you will dissolve a sample of NaCl in water and then measure the boiling point elevation for the solution. 1. Start Virtual ChemLab and select Boiling Point Elevation from the list of assignments. The lab will open in the Calorimetry laboratory with a calorimeter on the lab bench and a sample of sodium chloride (NaCl) on the balance. 2. Record the mass of the sodium chloride in the data table. If it is too small to read, click on the Balance area to zoom in, record the reading, and then return to the laboratory. 3. 100 mL of water is already in the calorimeter. Use the density of water at 25°C (0.998 g/mL) to determine the mass from the volume and record it in the data table. Make certain the stirrer is On (you should be able to see the shaft rotating). Click on the green heater light on the control panel to turn on the heater and begin heating the water. Click the clock on the wall labeled Accelerate to accelerate the laboratory time if necessary. 4. Observe the temperature until the first appearance of steam comes from the calorimeter. Immediately click the red light on the heater to turn it off and then record the temperature as the boiling point of pure water in the data table. Letting the water boil will decrease...
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...Melanie Mickens February 21, 2014 Statement of Purpose: The purpose of this lab was to determine the freezing temperature of the pure solvent, lauric acid, as well as finding the freezing temperature of a mixture of lauric acid and benzoic acid. Along with that, the freezing point depression of a mixture was to be calculated and along with the molecular weight of benzoic acid. Background: Colligative properties are properties which depend only on the number of solute molecules present in a solution and include freezing point depression, boiling point elevation, vapor pressure lowering, and osmotic pressure. The equation is ∆T=Kf *m Procedure: For part 1, add around 300 mL of tap water with a 20-25 C temperature into a 400 mL beaker, then putting it on the base of the ring stand. Use the utility clamp to get a test tube with the hot, melted lauric acid in it. Put the temperature probe in the lauric acid and secure the utility clamp to the ring stand. Lower the tube into the water making sure the water level outside the test tube is higher than the lauric acid level on the inside. Stir the acid up and down for ten minutes. After the data collection, use a hot water bath to melt the lauric acid enough to remove the temperature probe. Find the freezing temperature by mean temperature on the graph that had a fairly constant temperature. For Part 2, get a test tube that has the melted solution in it. After that, repeat the steps stated above starting at the part...
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...This effect is known as melting-point depression, and it is a colligative property because it depends on the concentration particles rather than their individual properties (Padias 2015). The compounds looked at in lab are crystalline solids, so they are arranged tightly in a particular lattice as a solid, and for the compound to melt those intermolecular forces holding the lattice together must be broken. However, when a foreign substance is introduced, the lattice is disrupted, meaning that the lattice is already being broken down before heat is added. Therefore, it takes less energy for the intermolecular forces to be broken to transition for a solid to a liquid, and the melting point occurs at a lower temperature. The more impure molecules there are, the more the lattice is disrupted, and the less energy it takes to melt (Brown et al.,...
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...Lab Instructor’s Name ____Samuel Lascio_ Student’s Name ___Atta Hassan____ Section # CHEM 101-___076_____ Experiment #__4_ Date of the experiment__10/26/15 Title__________Determination of molar mass by freezing point depression_______ ___________________________________________ ________________________ Drexel University Fall 2015 Introduction All substances have the characteristics to freeze or melt at some point even those we don’t usually seem (most likely because they need either extreme cold or extreme heat, which is usual to hot or cold for humans). But most substances can be identified by their freezing, or melting point. One example of a freezing and melting point would be water. Water freezes at 0 degrees Celsius into...
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...of Central Florida CHM 2046L Chemistry Fundamentals Laboratory (1 Credit) Course Syllabus Graduate Laboratory Instructor: Office: Phone: E-mail: Office Hours: | Instructor: Dr. Cherie YestrebskyOffice: CH 325Phone: 407-823-2135E-mail: cherie.yestrebsky@ucf.edu | University Course Catalog Description Illustration of chemical principles and introduction to the techniques of inorganic and physical chemistry. Course Overview The Chemistry Fundamentals Laboratory course is designed to give students an insight into the processes of experimental chemistry. The course provides a series of authentic, challenging, and relevant questions which students seek to answer through experimentation in a safe environment. Lab techniques like titration, spectroscopy, dilution, and measurement will be incorporated with critical thinking exercises to enhance the learning process and improve comprehension of fundamental concepts. An introduction to writing within the science discipline will be addressed each week. Course Objectives At the end of the semester, students will be able to: * Keep safety the first priority while working in the laboratory * Design a procedure to answer a key question * Model how writing is used in a variety of chemistry genres * Experiment with glassware & equipment in alignment with their intended function * Develop stronger critical thinking skills * Use laboratory terminology/vocabulary in text and...
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... Schalak while working on polyamides in IG Fabraen laboratory synthesized polycaprolactam through ring opening polymerization of caprolactom. He heated caprrolactam in a flask to about 250oC with about 5-10% water which hydrolyzed a few percent of the caprolactam to aminocaproic acid. The NH2 group of the aminocaproic acid acted as ring opening initiator for polycaprolactam followed by a polycondensation reaction of the NH2 and COOH group of the low molecular weight product of the ring opening polymerization reaction resulting in a high molecular weight product-Polycaprolactam. The key properties of polycaprolactam that have made them suitable for a variety of industrial applications are toughness, fatigue resistance, oil and abrasion resistance, high melting temperature, excellent fire resistance etc. The distinguishing feature that gives polycaprolactam these combinations of properties are the amide groups which are responsible for the strong hydrogen bonding between the adjacent polymer chains.These H- bonding brings the chains closer together increasing the crystallinity which accounts for...
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...Stoichiometry ________________________________________ Stoichiometry is simply the math behind chemistry. Given enough information, one can use stoichiometry to calculate masses, moles, and percents within a chemical equation. ________________________________________ ________________________________________ What is a Chemical Equation? In chemistry, we use symbols to represent the various chemicals. Success in chemistry depends upon developing a strong familiarity with these basic symbols. For example, the symbol "C"represents an atom of carbon, and "H" represents an atom of hydrogen. To represent a molecule of table salt, sodium chloride, we would use the notation "NaCl", where "Na" represents sodium and "Cl" represents chlorine. We call chlorine "chloride" in this case because of its connection to sodium. You should have reviewed naming schemes, or nomenclature, in earlier readings. A chemical equation is an expression of a chemical process. For example: AgNO3(aq) + NaCl(aq) ---> AgCl(s) + NaNO3(aq) In this equation, AgNO3 is mixed with NaCl. The equation shows that the reactants (AgNO3 and NaCl) react through some process (--->) to form the products (AgCl and NaNO3). Since they undergo a chemical process, they are changed fundamentally. Often chemical equations are written showing the state that each substance is in. The (s) sign means that the compound is a solid. The (l) sign means the substance is a liquid. The (aq) sign stands for aqueous in water and means...
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...CHM 1101 Introductory Chemistry Dawn Fox Medeba Uzzi August, 2007 Compiled and edited by Medeba Uzzi Authors’ Note This document is an initiative by the authors in an attempt to deal with what they think may be one of the reasons contributing to the relatively high failure rate in the introductory Chemistry course (CHM 1101) at the University of Guyana. It was brought to our attention that many first year students taking CHM 1101 are unable to efficiently cope with the frenetic pace of the Semester system and even less able to deal comprehensively with the large content in CHM 1101. It is hoped that by providing this paper, students will not need to make lots of notes in lectures and so they can focus on grasping the concepts taught. The document is meant to be a guide to the topics covered in CHM 1101 and is by no means exhaustive. Students are still required to attend classes regularly and punctually and to engage meaningfully in lectures and tutorials. Further, supplemental reading of these topics in any good General Chemistry text is expected. Dawn Fox Medeba Uzzi 2 SECTION 1 – Modules A – D: section deals with the foundation for chemistry. It introduces students to matter & its classification, Atom & its structure, Periodic table and chemical rxns. Introduction to Science and Measurement What is Chemistry? – Chemistry is the study of matter and its transformations Natural sciences refer to the systematic study of the natural world (our...
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...I. 진단혈액 진단혈액 수련항목 (1) : 혈액학적검사 기본 술기 표준수련기간 : 1주 수련내용 : ◆ 용어정의 : • 혈액학적검사 : 혈액세포와 응고에 관련된 일련의 검사를 의미한다. 혈구의 체내분포, 구조, 기능에 관련된 검사, 골수에 분포하는 전구세포에 관한 검사, 혈구에 영향을 끼칠 수 있는 혈장 인자에 관한 검사 및 유전자 이상에 관련된 검사 등을 포괄적으로 포함한다. • 망상적혈구수 : 적혈구 성숙 단계 중 정염색성 적아구(orthochromatophilic normoblast) 바로 다음 단계의 세포로 핵이 빠져나간 직후부터를 의미한다. 미토콘드리아, 중심소체(centriole), 리보솜 등을 함유하고 있으며 말초혈액에서 24-48시간의 성숙과정을 거쳐서 성숙한 적혈구로 된다 (Ref. Williams 16th p373-374) ◆ 숙지할 필수 지식 : • 혈액학 검사에 사용되는 검체와 항응고제의 작용기전 및 종류 • 모세관 혈액의 채취 방법과 용도, 채취 시 주의점 및 정맥혈과의 차이점 • 적혈구침강계수(ESR) 검사의 원리 ◆ 습득할 필수 술기 : • Neubauer chamber의 사용 • 미량법(micromethod)를 이용한 헤마토크리트의 측정 • 수기법을 이용한 망상적혈구수 검사 ◆ 국내외 장비 및 시약 현황 : 해당없음 ◆ 추천되는 참고자료 : • 대한혈액학회. 혈액학, 2006. • 대한진단검사의학회 편, 진단검사의학 제 3판, 2001. • Henry, JB. Clinical Diagnosis and Management by Laboratory Methods, 24th ed. 2006. 보고서 제출 일자 : 200 년 월 일 평가자 : 지도전문의 인 (일자 : 200 년 월 일) 과장 인 (일자 : 200 년 월 일) 수련위원 인 (일자 : 200 년 월 일) 진단혈액 수련항목 (2) : 자동 혈구계산기 표준수련기간 : 2주 수련내용 : ◆ 용어정의 : • 헤마토크릿(Hct) : 혈액 전체 부피에 대한 적혈구 부피의 비율, 단위는 % 또는 L/L • 평균적혈구용적(MCV) : 적혈구의 평균 용적, 단위는 fL, • MCV = Hct (L/L) X 1,000/RBC count (X1012/L) • 평균적혈구혈색소(MCH) : 적혈구 한 개당 혈색소 양, 단위는 pg, • MCH = hemoglobin (g/L)/RBC count (X1012/L) • 평균적혈구혈색소농도(MCHC) : 적혈구 한 개당 평균 혈색소 농도, • 단위는 g/L, MCHC = hemoglobin (g/L)/Hct (L/L) • 적혈구분포지수(RDW)...
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