Thermochemistry CHEM 101
Popular in Structural Chemistry, with Application to Chemistry of the Elements
Popular in Science
This 4 page Class Notes was uploaded by Piper Daniels on Thursday November 12, 2015. The Class Notes belongs to CHEM 101 at University of Alabama - Tuscaloosa taught by Mrs. Leung in Summer 2015. Since its upload, it has received 16 views. For similar materials see Structural Chemistry, with Application to Chemistry of the Elements in Science at University of Alabama - Tuscaloosa.
Reviews for Thermochemistry
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: 11/12/15
Chapter 10 Thermochemistry November 12 2015 Thermodynamics 1 Thermodynamics is the study of energy exchange 2 Law of Conservation of Enerov energy is never created nor destroyed a Energy can be transferred system lt gt surrounding b Energy can be transformed potential lt gt kinetic c System user defined i For reactions molecules atoms d Surrounding everything else that the system can exchange energy with i For reactions solvent bench beaker air around the beaker 3 First law of thermodynamics the total energy in the universe is constant a Universe system and surrounding b AEnergy of Universe O Energyfinal Energyinitial c AEnergy of Universe AEsystem AEsurrounding d AEsystem 39AEsurrounding 939 AEsystem AEsurrounding Energy Diagram 1 Enerqv diagram graphical way to show the direction of energy flow 2 1 Flueactan39ts Products a Reactants are the system at the beginning of the reaction b Products are the system at the end of the reaction C AEsystem Efinal Einitial Eproducts 39 Ereactants 3 Exothermic energy flows out of the system to the surrounding a system gt surrounding b System lost energy decrease in energy more stable c Surrounding gain energy increase in energy less stable 4 Exothermic reactions reactants energy is higher than the products a39 Eproducts Ereactants b Energy will always end up being a negative value think system is losing energy 5 Endothermic energy flows into the system a system lt surrounding b System gain energy less stable c Surrounding lost energy more stable 6 Endothermic Reactions products energy is higher than the reactants 3 AE Eproducts39 Ereactants b Energy will always end up being positive think system is gaining energy Internal Energy 1 Internal Enerqv I is the sum of KE PE in the system a E KE PE b state function depends on the state of the system not the path taken i depends on initial final state only ii see 2 for an example of this 2 CH4g 202g gt C s 2H2g 202g a decomposed b Cs 2H2g 202g gt 0020 2HgOCl 0 CH4g 2029 gt C029 2H20g d all that really matters is what you start with and what you end with not the inbetween of it all i this is because you only care about nal and initial ii combustion reactions will ALWAYS lose energy energy is negative exothermic 3 system lt gt surrounding a E internal energy b transferred through q heat and w work i units for q and w are Joules 4 Heat q a Positive value system gains heat i temperature increases ii surrounding temperature decreases b Negative value system lostreleased heat i temperature decreases ii surrounding temperature increases 5 Work VV a Positive value system gains work i surrounding worked on the system b Negative value system lost work i system did work on the surrounding Heat 1 M q is the exchange of thermal energy between the system and the surrounding a can be measured by the change in temperature b ATTfinalTinitial 2 Hot substance gt cold substance a the flow of heat stops at thermal equilibrium when the temperature of both substances are the same 3 Heat qcAT a cheat capacity J C b AT change in temperature c Heat capacity the quantity of heat required to change the temperature by 1 C d C is an extensive prooertv depends on the quantity and identity of the substance 4 5g H20 vs 10g H20 a 5g i smaller c because less substance ii C209 J C iii AT1 C iv qx larger c because more substance ii C418 J C iii AT1 C iv q2x because double the sample it s linear c C determined for each sample since it depends on quantity and identity Specific Heat Capacity 1 Specific Heat Capacity Cs the amount of heat required to raise the temperature of 1g of a substance by 1 C 2 Units Jg C 3 CmCs qmCAT mCSAT mmass g CsJg C 4 10g H20 vs 10g Au a H20 i Cs 418 Jg C ii AT 1 C iii requires more heat to change the temperature b Au i CSO128 Jg C ii AT 1 C Molar Heat Capacity 1 Molar Heat Capacitv Cm the amount of heat required to raise the temperature of 1 mole of substance by 1 C a Cm C8 molar mass b C8 Cm molar mass c q mCSAT mCmAT molar mass d q nCmAT i nmoles HeatEqua ons 1 q CAT 2 CmCs gt qmCSAT 3 Cmmolar massCS gt qnCmAT Thermal Energy Transfer 1 Hot substance gt cold substance 3 39qhot qcold b qhot qcold 2 39qhot qcold mhotCshotAT m C AT cold scold a at thermal equilibrium final temperature of hot and cold are the same Things to Memorize 1 Boiling Point of H20 100 C 2 Freezing Point of H20 0 C 3 Room Temperature 25 C 4 dH20 100 gmL a 1 mL 1cm3 Work 1 PressureVolume Work a wPAV b typically used with pistons i pressure from the piston is considered the surrounding ii the air inside is the system compressed vs expanded
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'