...lee (ml37757) – Ch 5 Thermochemistry – tetzlaff – (201201) This print-out should have 27 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points What factor determines whether a reaction will be exothermic or endothermic? 1. the difference in energy between reactants and products 2. the speed of the reaction 3. the relative concentrations of reactants and products in solution 4. the heat properties of the products 1. +350 kJ 5. the activation energy of the reaction 2. −50 kJ 002 10.0 points Refer to the potential energy diagram shown below. 10 350 9 8 7 6 300 5 4 3 2 250 1 0 1 003 10.0 points Refer to the potential energy diagram shown below. 10 550 9 8 7 6 450 5 4 3 2 350 1 0 Energy (kJ) A B 0 1 2 3 progress 8 9 101112 rxn 4 5 6 7 What is the change in enthalpy (∆H) for the reaction A → B? 3. −350 kJ 4. −100 kJ 5. +100 kJ Energy (kJ) B 004 10.0 points An endothermic reaction corresponds to one in which 1. ∆H is negative; heat is absorbed 0 1 2 3 progress 8 9 101112 rxn 4 5 6 7 A 2. ∆H is positive; heat is absorbed 3. ∆H is negative; heat is evolved 4. ∆H is positive; heat is evolved What is the change in enthalpy (∆H) for the reaction A → B? 1. −250 kJ 2. −150 kJ 3. +300 kJ 4. +50 kJ 5. −50 kJ 005 10.0 points Which statement would be the best interpretation of the First Law of Thermodynamics? 1. The total amount of energy in the universe is increasing. 2. The total...
Words: 1922 - Pages: 8
...Centre for Foundation Studies, UTAR 1 2 Chapter Scopes • Endothermic & Exothermic reactions • Enthalpy changes: ∆H of formation, combustion, hydration, neutralization, atomization. CHAPTER 5 Chemical Energetic / Thermochemistry • Lattice energy, electron affinity • Heat of fusion and vaporization • Hess’ Law • Born-Haber cycles • Calorimetry © 2006 Brooks/Cole - Thomson © 2006 Brooks/Cole - Thomson 3 Energy & Chemistry 4 Thermochemistry • Thermochemistry is the study of heat (energy) change/transfer in a chemical reaction. • ENERGY is the capacity to do work or transfer heat. • HEAT is the transfer of thermal energy between two objects because of their difference in temperature. Heat energy is associated with molecular motions. Other forms of energy light electrical kinetic and potential Heat transfers until thermal equilibrium is established. ∆T measures energy transferred. © 2006 Brooks/Cole - Thomson © 2006 Brooks/Cole - Thomson System and Surroundings 5 System and Surroundings 6 Vacuum jacket • SYSTEM – The object under study • SURROUNDINGS – Everything outside the system © 2006 Brooks/Cole - Thomson FHSC1114 Physical Chemistry open Exchange: mass & energy closed energy isolated nothing © 2006 Brooks/Cole - Thomson 1 Centre for Foundation Studies, UTAR Directionality of Heat Transfer 7 Directionality of Heat Transfer • Heat always transfer...
Words: 2559 - Pages: 11
...Centre for Foundation Studies, UTAR 1 2 Chapter Scopes • Endothermic & Exothermic reactions • Enthalpy changes: ∆H of formation, combustion, hydration, neutralization, atomization. CHAPTER 5 Chemical Energetic / Thermochemistry • Lattice energy, electron affinity • Heat of fusion and vaporization • Hess’ Law • Born-Haber cycles • Calorimetry © 2006 Brooks/Cole - Thomson © 2006 Brooks/Cole - Thomson 3 Energy & Chemistry 4 Thermochemistry • Thermochemistry is the study of heat (energy) change/transfer in a chemical reaction. • ENERGY is the capacity to do work or transfer heat. • HEAT is the transfer of thermal energy between two objects because of their difference in temperature. Heat energy is associated with molecular motions. Other forms of energy light electrical kinetic and potential Heat transfers until thermal equilibrium is established. ∆T measures energy transferred. © 2006 Brooks/Cole - Thomson © 2006 Brooks/Cole - Thomson System and Surroundings 5 System and Surroundings 6 Vacuum jacket • SYSTEM – The object under study • SURROUNDINGS – Everything outside the system © 2006 Brooks/Cole - Thomson FHSC1114 Physical Chemistry open Exchange: mass & energy closed energy isolated nothing © 2006 Brooks/Cole - Thomson 1 Centre for Foundation Studies, UTAR Directionality of Heat Transfer 7 Directionality of Heat Transfer • Heat always transfer...
Words: 2559 - Pages: 11
...Tutorial 5: Chapter 5 Chemical Energetics / Thermochemistry 1. A 9.36 g of platinum is heated to 98.6 °C and dropped onto ice. When the metal’s temperature has dropped to 0.0 °C, it is found that 0.37 g of ice has melted. Determine the specific heat capacity of platinum. (Given the latent heat of fusion for ice is 333 J g -1 .) 2. A 72.8 g of copper at 143.2 °C is added to an insulated vessel containing 165 mL of glycerol (density = 1.26 g mL-1 ), at 24.8 °C. The final temperature is 31.1 °C. The specific heat capacity of copper is 0.385 J g-1 °C-1 . (a) Determine the mass of glycerol. (b) Determine the heat released from the copper. (c) Determine the specific heat capacity of glycerol in J g-1 °C-1 . (Ans: 2.4 J g-1 °C-1 ) [Dec 2014] 3. (a) Acetic acid, CH3COOH, is made industrially by the reaction of methanol and carbon monoxide as shown by the following equation: CH3OH(l) + CO(g) → CH3COOH(l) ΔHrxn = 355.9 kJ Determine the amount of heat evolved when 0.5 L of acetic acid is produced. (Given the density of CH3COOH is 1.044 g mL-1 ) (b) The molecule N2O4 is a dimer of the molecule NO2. The enthalpy of formation of N2O4 and NO2 are +9.67 kJ mol-1 and +33.86 kJ mol-1 respectively. Calculate the standard enthalpy of reaction, in kJ mol-1 for the formation of N2O4 from NO2. 4. The combustion of one mole of ethylene (C2H2) gas to form carbon dioxide and water releases 1299.4 kJ of heat energy. (a) Write a balanced thermochemical equation for this...
Words: 470 - Pages: 2
...During the experiment we encountered various problems. While weighing the magnesium, some of the strips fell and other strips fell off, therefore we had to weigh it again. When we did the first reaction, the final temperature of the reaction rose to only about 65C due to the fan and air conditioning in the area that we were working in. We consulted with the instructor, and he told us that the final temperature had to be at least 70C. We moved to another area where the fan was not blowing directly at us, and we did the first reaction again, finally obtaining the desired temperature. The next problems we encountered were in the calculations of the enthalpy for the reaction: Mg(s) + 1/2O2(g) MgO(s) At first, we forgot to change the enthalpies from the reactions that we produced to kilo Joules. Then, we consulted the instructor with our final answer, he said that we had to divide the enthalpies we found from the reactions that we produced by .05 mol, in order to calculate it with the other enthalpies, because the unit for enthalpy is kJ/mol. Theoretical Value: Mg(s) + 1/2O2(g) MgO(s) H = -601.8 kJ Experimental Value: Mg(s) + 1/2O2(g) MgO(s) H = -578.4 kJ Our experimental value is -23.4 kJ more than the theoretical value. Compared to the theoretical value, our percent error is: Percent Error: 578.4 kJ - 601.8 kJ x 100 % 601.8 kJ ...
Words: 627 - Pages: 3
...Thermochemistry Discussion Questions 1. Report the mean ΔHrxn for each part with standard deviation and % error. The mean ΔHrxn for the heat of neutralization was calculated to be -49 kj/mol with a standard deviation of ±2 and a % error of -12%. The mean ΔHrxn for the heat of solution was calculated to be -23 with a standard deviation of ±2 and a % error of -22%. 2. Looking at the % errors, comment on the accuracy of each experiment. For the heat of neutralization, the percent error was calculated to be -12%. For the heat of solution, the percent error was calculated to be -18%. Because both percent errors are greater than the accuracy threshold of ± 10%, neither measurement is accurate. 3. Looking at the standard deviations, comment on the precision of each experiment. The standard deviation for the heat of neutralization, which was ±2, was precise because the mean ΔHrxn was calculated to be -47kj/mol. Because a significant figure did not have to be dropped, the measurement was precise. The standard deviation for the heat of solution, which was also ±2, was precise because the mean ΔHrxn was calculated to be -49 kj/mol. Because a significant figure did not have to be dropped, the measurement was also precise. 4. Why is the sign of heat gained or lost by a reaction the opposite sign of the heat gained or lost by the solution? The sign of heat gained or lost by a reaction is the opposite sign of the heat gained or lost by the solution because as...
Words: 870 - Pages: 4
...Pechelbronn – 6 August 1930, in Paris, France) was a French chemist. He is best known for his work in stereochemistry. Le Bel was educated at the École Polytechnique in Paris. In 1874 he announced his theory outlining the relationship between molecular structure and optical activity. This discovery laid the foundation of the science of stereochemistry, which deals with the spatial arrangement of atoms in molecules. This hypothesis was put forward in the same year by the Dutch physical chemist Jacobus Henricus van 't Hoff. Le Bel wrote Cosmologie Rationelle (Rational Cosmology) in 1929. 2. Pierre Eugène Marcellin Berthelot (25 October 1827 – 18 March 1907) was a French chemist and politician noted for the Thomsen-Berthelot principle of thermochemistry. He synthesized many organic compounds from inorganic substances and disproved the theory of vitalism. He is considered as one of the greatest chemists of all time. He was born in Paris, France, the son of a doctor. After doing well at school in history and philosophy, he became a scientist. 3. Yves Chauvin (born October 10, 1930) is a French chemist and Nobel Prize laureate. He is honorary research director at the Institut français du pétrole and a member of the French Academy of Science. Chauvin received his degree from the Lyon School of Chemistry, Physics and Electronics in 1954. 4. Arne Wilhelm Kaurin Tiselius (10 August 1902 – 29 October 1971) was a Swedish biochemist who won the Nobel Prize in Chemistry in 1948. 5...
Words: 813 - Pages: 4
...Marking Period Matter Atomic Structure Radioactivity Electron Clouds and Probability Fall Semester: 2nd Marking Period Periodic Table Periodic Properties Chemical Nomenclature Chemical Reactions Fall Semester: 3rd Marking Period The Mole Stoichiometry Chemical Bonding Polarity of Molecules TEXTBOOK/REFERENCE Zumdahl, Zumdahl and DeCoste. 2003. The World of Chemistry. McDougall Littel MATERIALS Bound Composition Notebook (for taking notes) scientific calculator Bound Composition Notebook (for homework) binder paper Blue/black pen for writing graphing paper Red pen for correcting papers other materials (announced as the need arises) One roll of paper towel or box of tissues (per school year) Spring Semester: 1st Marking Period Phase Changes Thermochemistry Reaction Rates Chemical Equilibrium Spring Semester: 2nd Marking Period Gases and the Mole Solutions and Solubility Acids and Bases Biochemicals and Polymers Spring Semester: 3rd Marking Period Colligative Properties Hess’s Law/Enthalpy of Reaction Titration...
Words: 809 - Pages: 4
...Physical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of laws and concepts of physics. * Chemical kinetics, also known as reaction kinetics, is the study of rates of chemical processes. Chemical kinetics includes investigations of how different experimental conditions can influence the speed of a chemical reaction and yield information about thereaction's mechanism and transition states, as well as the construction of mathematical models that can describe the characteristics of a chemical reaction. * Chemical physics is a subdiscipline of chemistry and physics that investigates physicochemical phenomena using techniques from atomic and molecular physics and condensed matter physics; it is the branch of physics that studies chemical processes from the point of view of physics. * Electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor (theelectrode: a metal or a semiconductor) and an ionic conductor (the electrolyte). * Femtochemistry is the area of physical chemistry that studies chemical reactions on extremely short timescales, approximately 10–15 seconds (one femtosecond, hence the name). The steps in some reactions occur in the femtosecond timescale and sometimes in attosecond timescales,[1] and will sometimes form intermediate products. * Geochemistry is the science that uses the tools and principles...
Words: 1073 - Pages: 5
...Department of Chemistry College of Sciences University 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 ...
Words: 1506 - Pages: 7
...THERMOCHEMISTRY OF NaOH AND HCl LAB Overview Teacher’s Instruction: Find the Molar Heat of Reaction for the NaOH reaction. Then, predict and calculate the change in enthalpy (ΔE) and change in heat (ΔH) when 5.00g NaOH reacts completely with HCl. Reaction Equation: NaOH(s) + HCl(aq) -> NaCl(aq) + H2O(liq) Net Ionic Equation: Na(OH)(s) + H+(aq) -> H2O(liq) + Na+(aq) The Big Question: If we combine solid NaOH and aqueous HCl, how will the temperature change? What will the change be with, specifically, 5.00g of NaOH? Scientific Background and Principle: WELL, I’ll have you know that we got our hands on a fancy-schmancy Lab Quest 2 with a temperature probe. Now this device allows us to accurately record the temperature of a given entity over a period of time; as such, by having the Lab Quest record the temperature of the system, we were able to gather the total temperature change for the reaction. In theory, the temperature should increase by 53.10o Variables * Independent Variable: Amount of NaOH * We had a theoretical value for temperature that was dependent on the amount of NaOH used; as such, we set our amount at a certain point to achieve that temperature. * Dependent Variable: Heat of Reaction (Temperature) * We measured the temperature of the reaction throughout its duration, which would have varied in intensity and duration based on the amount of NaOH we used * Controlled Variables * Light-- by enclosing the reaction in darkness...
Words: 1848 - Pages: 8
...Chemistry -Study of the composition, structure, properties, and interactions of matter. -Central Science. BRANCHES OF CHEMISTRY 1. Inorganic chemistry is the study of the chemical nature of the elements and their compounds (except hydrocarbons—compounds composed of carbon and hydrogen). Involves substance that do not contain carbon or substances from non-living things. 2. Organic Chemistry, branch of chemistry in which carbon compounds and their reactions are studied. A wide variety of classes of substances—such as drugs, vitamins, plastics, natural and synthetic fibers, as well as carbohydrates, proteins, and fats—consist of organic molecules. Study of all substance containing carbon in combination of hydrogen, oxygen, nitrogen and other elements. 3. Analytical chemistry is the science of separating complex materials into simpler ones and detecting and measuring the constituents. 4. Physical chemistry is fundamental to all chemistry and deals with the application of physical laws to chemical systems and chemical change. Concerned with theories and experiments that describes the behaviour of chemicals. 5. Biochemistry is the chemistry of living organisms and life processes. Cell: Compound 1. Protein 2. Carbohydrates - sugar 3. Nucleic acid – DNA, RNA 4. Lipids – fats SCIENTIFIC METHOD * A logical approach to the solution of the problem. STEPS: 1. Identify the problem 2. Gathering Information 3. Formulate hypothesis 4. Experimentation...
Words: 2871 - Pages: 12
...things in everyday living. Relevance of your testable question * Graphite will be the main material used on this project: which is the pencil lead. It is an electrical conductor, which allows many electrical possibilities. It is one of the allotropes of carbon, which in the next paragraph I will give a brief description from Wikipedia. Graphite is considered a semimetal, so there are many electrical possibilities that can be done with it. Along with many other uses for it. Allotropes (Graphite) “unlike a diamond, graphite is an electrical conductor. Thus, it can be used in, for instance, electrical arc lamp electrodes. Like wise, under standard conditions, graphite is the most stable form of carbon. Therefore, it is used in thermochemistry as the standard state for defining the heat formation of carbon compounds.” (Definition retrieved from Wikipedia) Literature review The literature I used and the websites were very helpful. They gave me idea on how to conduct the following experiment. I went even further and talked to my grandpa who was an electrical engineer for Boeing, to help also further explain the process that would be taking place. Science buddies websites that was done by: Sara Agee Ph. D was the most helpful in guiding me through this experiment. Other...
Words: 3874 - Pages: 16
...CHEMISTRY CHEMISTRY (CLASSES XI–XII) Rationale Higher Secondary Stage is the most crucial stage of school education because at this stage specialised discipline based, content oriented courses are introduced. Students reach this stage after 10 years of general education and opt for Chemistry with a purpose of mostly for pursuing their career in basic sciences or professional courses like medicines, engineering, technology and studying courses in applied areas of science and technology at tertiary level. Therefore, at this stage, there is a need to provide learners with sufficient conceptual background of Chemistry, which will make them competent to meet the challenges of academic and professional courses after the higher secondary stage. National Curriculum Framework for School Education – 2005 recommends a disciplinary approach with appropriate rigour and depth with the care that syllabus is not heavy and at the same time it is comparable to the international level. It emphasizes a coherent focus on important ideas within the discipline that are properly sequenced to optimize learning. It recommends that theoretical component of Higher Secondary Science should emphasize on problem solving methods and the awareness of Syllabus for Secondary and Higher Secondary Levels 22 historical development of key concepts of science be judiciously integrated into content. The present exercise of syllabus development in Chemistry at Higher Secondary Stage is based on this framework...
Words: 3687 - Pages: 15
...How has density functional theory improved for chemical applications? Discussion of some of the recent developments [0] Table of Contents Introduction3 Roots of DFT…………………………………………………………………………………………………………………………………………….3 Modern DFT4 Modifications6 Basis Sets6 Finding the EXC energy6 Hybrid Functionals8 Double Hybrid10 Strengths of DFT10 Challenges for DFT11 Current research12 Conclusions15 Introduction It has become an accepted fact that computational chemistry has become the partner to experimental chemistry. This is because computational experiments supplement real world experimental data very well. There are many systems in which there is no possible way of getting data about them, and so we must turn to computational methods. One example of this is looking at transition states, which in the real world may only exist for fractions of a second, however with the help of computational methods; we are able to investigate them easier, cheaper and quicker. There are many methods for computational chemistry experiments, however in this paper we will be focusing on how density functional theories (DFT) has impacted the chemistry community. The review will show how DFT started as an alternative to Schrodinger wave function methods, with simulated homogeneous electron gases, and moved on to be non-local, including other short and long range potentials and also combining empirical data to improve on the functionals. How DFT has its strengths and weaknesses and...
Words: 4644 - Pages: 19
