Lecture 12 Notes
Lecture 12 Notes CHE 106 - M001
Popular in General Chemistry Lecture I
CHE 106 - M001
verified elite notetaker
Popular in Chemistry
This 4 page Class Notes was uploaded by Madeline Merwin on Sunday October 18, 2015. The Class Notes belongs to CHE 106 - M001 at Syracuse University taught by R. Doyle in Fall 2015. Since its upload, it has received 25 views. For similar materials see General Chemistry Lecture I in Chemistry at Syracuse University.
Reviews for Lecture 12 Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 10/18/15
CHE 1015 Lecture 12 We will not rush it so we will not get through this lecture day so it will pick up next week Chapter 5 Thermodynamics Theremoheat dynamicsmovement Heat owamics The science of the relationship between heat and energy 0 Thermochemistry is the study of the quantity of heat absorbed or evolved by chemical reactions The Laws of thermodynamicsZeroth You must play the game First You can39t win Second You can39t break even Third You can39t quit the game 1St aka Law of Conservation of Energy states that energy cannot be created or destroyed in a chemical reaction 2nd he second law of thermodynamics states that the entropy of any isolated system not in thermal equilibrium almost always increases 3rd The third law of thermodynamics states that the entropy of a system approaches a constant value as the temperature approaches absolute zero If you obtain absolute zero you can stop absolute chaos but that is unattainable SIDE NOTE Gibbs free energy The energy associated with a chemical reaction that can be used to do work The free energy of a system is the sum of its enthalpy H plus the product of the temperature Kelvin and the entropy S of the system G H TS Free energy of reaction 1395 G The change in the enthalpy 5 H of the system minus the product of the temperature Kelvin and the change in the entropy 5 S of the system 11G 11H T118 Thermochemistry is the study of the quantity of heat absorbed or evolved by chemical reactlon Enthalpy is a state function depends on how much is there Energy is the ability to move matter or to do work The ability to do stuff It can be many forms matter is a form of energy 1 Radiant energy ex inerfed electromagnetic radioation 2 Thermal energy Essential the motion of molecules or atoms 3 Chemical the energy stored in bonds For humans we store this as ATP I wonder what dinosaur cells looked like There are 3 overall broad concepts of Energy 1 Kinetic energy the energy associated with an object by virtue of its motion 2 Potential Energythe energy an object has by virtue of its position in a field of force EX Humans and gravity 3 Internal Ethe sum of the kinetic and potential energies of particles of a substance Win a substance there is energies in the particles that make up the substance 1 Kinetic E an object of mass m and speed or velocity V have energy Ek This shows that the kinetic E of an object depends on both its mass and its speed Exam Q consider the kinetic E of a person of mass 130 lbs 59 kg traveling in a car at 60 mph 268 ms Ek 1259o kgX288 msquot2 Ek2l2X10 quot4 kg X msquot2aka a Joule 6184 Jl calories 1 cal4184 J 2 Poential Energy the E depending on the virtue of the position in an applied field of force EX Water in a damn of mass m has a position h in a gravitational field g of Epmgh Simple use of your brain to get EX What is the Ep of 1000 lb of water at the top of a 300 ft dam 4536 kg X 980 msquot2 X 9144 m Ep406 X 10 quot5 kg X mquot2squot2 or 406 X 10quot5 J Energy can be converted but never destroyed it is conserved lst thermodynamics law NOTE that books use Etotal but in this class we use U U is the energy of the particles making up a substance So the total energy Law of conservation of Energy which states that energy may be conserved into one form or the other but the total quantity of EnergyEtotalremains constant A same as the first law of thermodynamics Heat of Reaction Heat is as the energy that ows into or out of a system because of the difference in temperature between the system and its surroundings Heat and temp are not the same Heat has a mass component temp does not Heat ows from a region of higher temperature to one of lower temperature once the temperatures are equal heat ow stops and thermal equilibrium is reached It aaaall boils down to the universe trying to reach thermal equilibrium to share the energy in essence Heat itself is denoted at q If q is heat is absorbed by the system Endothermic reaction Heat into a system If q is heat is evolved from the system Exothermic reaction Heat out of a system The heat of reaction is the value of q required to return a system to its original temperature after a reaction How much energy would be required to take you up and pick you up off the ground once you ve jumped and hit the bottom We look at it this way so we are able to physically measure it We grasp it from back to front View is from equilibrated hot cup of coffee to hot cup of coffee Based on scientists ability to perform and experiment Enthalpy and its change The heat absorbed or evolved depends on the conditions in which it occurs Usually a reaction occurs in an open vessel at atmospheric pressure If you change pressure you will change the protein The heat of this type of rxn is denoted by qp heat at constant pressure You have to denote the pressure bc it plays a major fole on Q and energy ow TO obtain the heat absorbed or eveolved in a chemical rexm you use extensive properties Enthalpy aka H is a state function An extensive property of a substance that can be used to obtin the heat absorbed or evolved in a chemical rxn An extensive property is one that depends on the quantity of substance mass volume a state function is a property of the system that depends only on its present state and so is independent on any previous history Enthalpy The change in enthalpy AH Deltachange triangle You don t actually measure H you only measure the change in H Because this is thermoDYNAMICS energy is changing movement The change in enthalpy for a rxn at a given temp and pressure which is called the enthalpy of rxn is obtained by subtracting the enthalpy of the reactants from the enthalpy of the products AHH H products reactants EX A neg delta H 3686 This means that 3686 is released This represents the entire change in internal energy HI minus any expansion work done by AH q p the system Enthalpy and internal Energy U is defined as the heat at constant pressure qp plus the workw done by the system U q p w W the change in vol at a given pressure AU AH PAV This means that internal EU changes by energy entering or leaVing H1 or the system increase or decreases in volume PDV A thermochemical equation is the chemical equation for a reaction including phase labels in Which the equation is given a molar interpretation and the enthalpy of reaction for these molar N2g 3H2g gt 2NH3g AH 918 k amounts is written directly after the equation EX It s important to note phase labels because the enthalpy change DH depends on the phase of the substances
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'