# Chem test 4

 What two conditions need to be met for a reaction to be spontaneous? ΛG<0 and K>1 What is the Gibbs Free Energy equation? ΛG= ΛH- TΛS What is entropy? A change in randomnessIncreases with all spontaneous reactions (2nd law of thermodynamics) What is the first law of thermodynamics? Energy cannot be created or destroyed What is thermodynamics? A prediction about whether or not a reaction will occur under the given conditions How to calculate ΛG in standard conditions: ΛGrxn= ΛHrxn- TΛSrxn Or  ΛGrxn= ΣnΛGf (products) - ΣnΛGf (reactants) How to calculate ΛG under non-standard conditions: ΛG= ΛG(naught)+ RTlnQ Where R = 8.314 J/mol*K When at equilibrium: ΛG= -RTlnK What are the factors that affect entropy? State: gas>liquid>solidMolecular mass and complexity: more = more entropyAllotropy: More irregular = higherDissolution: Solution>pure solvent/ solute alone What are the standard states? Gas: pure gas at 1 atm Solid Liquid: Pure solid/liquid in it's most stable formTemperature: 25CSolution: Solute concentration 1M What is the faraday constant? 96,485 F What is solubility? How well something dissolves from a solid to an aqueous substance Is E(cell) positive or negative when a reaction is spontaneous? Positive Nernst Equation Ecell= E(cell)- 0.0592/n(logQ) Calculating E(cell) E(cell)= E (reduction)- E(oxidation) (Cathode-anode) What is controlled by entropy and enthalpy? Spontineity (ΛS) Calculating standard entropy change (spontaneity) ΛSrxn= ΣnΛS (products) - ΣnΛS(reactants) Calculating change in enthalpy (ΛH) ΛHrxn= ΣnΛH (products) - ΣnΛH (reactants) Factors that affect solubility Common ion effect- Adding ions shifts equation to the left, because [] of ions has increasedpH effect- Metal hydroxides are more soluble when the pH is low (basic)Compounds containing anions that are the conjugate bases of weak acids are more soluble with a low pH (basic) How is precipitation predicted with Q values? Q>1, precipitation forms. Reaction shifts left Q<1, no precipitation forms. Reaction shifts rightQ=1, precipitation on the cusp of forming. Reaction does not shift What is Ksp The solubility constant How does ΛS effect entropy? ΛS>0, more random. Favors spontaneity ΛS<0, less random. Does not favor spontaneity On the standard electrode potential chart, the most negative is the best ____ agent Reducing On the standard electrode potential chart, the most positive is the best ____ agent Oxidizing What occurs at the anode and what is its charge? Oxidation Negative (anion) What occurs at the cathode and what is its charge? Reduction Positive (cation) What is the common oxidation number of O2? -2 What is the oxidation number of an element? 0 What is the oxidation number of a monatomic ion? It's charge AuthorBagelHyrax ID355295 Card SetChem test 4 DescriptionEquations and concepts for chem 111 test 4 Updated2021-05-05T18:44:17Z Show Answers