Chemistry XI Unit 5 Questions: 69 Time Limit: 69 minutes Passing Score: 60% Start Quiz Chemistry XI Unit 5 Question 1 of 69 Thermodynamics is the study of: atomic structure heat and energy changes chemical bonding electron configuration The First Law of Thermodynamics states: energy is created energy is destroyed energy is conserved; ΔU = q + w heat flows from cold to hot Internal energy (U) is: kinetic energy only potential energy only sum of all kinetic and potential energies heat energy only In thermodynamic notation, q represents: work done heat energy internal energy free energy In thermodynamic notation, w represents: work done on/by system heat absorbed internal energy entropy An exothermic reaction: absorbs heat releases heat has ΔH > 0 requires activation energy An endothermic reaction: releases heat absorbs heat spontaneous always releases light Enthalpy (H) is defined as: H = U + PV H = U - PV H = U × PV H = U / PV For a reaction at constant pressure, ΔH equals: ΔU q (heat absorbed/released) w (work done) ΔU - w Hess's Law states: heat is conserved enthalpy change independent of path entropy always increases energy is destroyed Entropy (S) is measure of: energy lost as heat disorder/randomness temperature change pressure change The Second Law of Thermodynamics states: ΔS > 0 always ΔS(universe) ≥ 0 for spontaneous processes all reactions are exothermic all reactions are endothermic Gibbs free energy (G) is defined as: G = H - TS G = H + TS G = U + PV G = ΔH - TΔS A reaction is non-spontaneous when: ΔG > 0 ΔG < 0 ΔH < 0 ΔS > 0 At equilibrium: ΔG = 0 ΔG ≠ 0 ΔH = ΔG q = w Heat capacity is the amount of heat needed to: burn substance change temperature by 1°C melt substance vaporize substance Standard enthalpy of formation (ΔHf°) is: energy in standard state element energy to form 1 mole from elements in standard state energy to burn compound energy to melt substance Hess's Law allows calculation of: ΔH for reaction if direct measurement difficult atomic mass molecular weight density Spontaneous processes at all temperatures: ΔH < 0, ΔS > 0 ΔH > 0, ΔS < 0 ΔH > 0, ΔS > 0 ΔH < 0, ΔS < 0 Temperature dependent spontaneity occurs when: ΔH < 0, ΔS > 0 ΔH > 0, ΔS < 0 ΔH > 0, ΔS > 0 ΔH < 0, ΔS > 0 at high T In calorimetry, q = mcΔT where: m is molar mass c is specific heat capacity c is heat of vaporization m is momentum The heat of vaporization is: heat to melt solid heat to convert liquid to gas heat to burn substance heat to expand substance The heat of fusion is: heat to convert solid to liquid heat to convert liquid to gas heat to burn substance heat to sublime Sublimation is: melting process transition solid → gas directly boiling process condensation process The equation ΔG° = -RT ln(K) relates: free energy to equilibrium constant heat to entropy pressure to volume temperature to mass For a reaction with ΔH = -100 kJ and ΔS = 50 J/K at 300 K: spontaneous at low T spontaneous at high T nonspontaneous at all T spontaneous at all T Work in thermodynamics includes: heat transfer only expansion against external pressure temperature change only entropy change Reversible process in thermodynamics: always fast always spontaneous can reverse with infinitesimal change requires no energy Irreversible process: impossible to reverse naturally occurs one direction requires energy to reverse impossible in universe FILLBLANK:_____ is change in internal energy. ΔU ΔH ΔS ΔG FILLBLANK:_____ represents heat transferred. q w Q H FILLBLANK:_____ represents work done. w q W P FILLBLANK:Reactions that release heat are _____. exothermic endothermic isothermal adiabatic FILLBLANK:Reactions that absorb heat are _____. endothermic exothermic spontaneous isothermal FILLBLANK:_____ is total energy (internal + flow) Enthalpy Entropy Gibbs energy Helmholtz energy FILLBLANK:The Second Law: _____ increases for universe. Entropy Energy Temperature Enthalpy FILLBLANK:When ΔG < 0, reaction is _____. spontaneous non-spontaneous equilibrium reversible FILLBLANK:When ΔG > 0, reaction is _____. non-spontaneous spontaneous at equilibrium irreversible FILLBLANK:At equilibrium, ΔG = _____ zero negative positive undefined FILLBLANK:The _____ is energy to form 1 mole from elements. standard heat of formation heat of combustion heat of fusion heat of vaporization FILLBLANK:Calorimetry equation: q = _____ mcΔT nΔH PΔV ΔG FILLBLANK:The _____ is energy to convert liquid to gas. heat of vaporization heat of fusion heat of sublimation heat of combustion FILLBLANK:The _____ is energy to convert solid to liquid. heat of fusion heat of vaporization heat of sublimation heat of condensation FILLBLANK:When ΔH > 0, TΔS > ΔH: reaction is spontaneous at _____. high temperatures low temperatures all temperatures zero temperature FILLBLANK:When ΔH < 0, ΔS > 0: reaction is spontaneous at _____. all temperatures high temperatures low temperatures no temperatures FILLBLANK:_____ is transition from solid directly to gas. Sublimation Deposition Melting Vaporization FILLBLANK:In ΔG° = -RT ln(K), K is _____. equilibrium constant rate constant solubility product ionization constant FILLBLANK:_____ is amount of energy before reaction. Activation energy Kinetic energy Potential energy Free energy FILLBLANK:Reaction that absorbs heat from surroundings is _____. endothermic exothermic isothermal adiabatic FILLBLANK:Reaction that releases heat to surroundings is _____. exothermic endothermic spontaneous reversible FILLBLANK:The _____ cannot be created or destroyed. energy matter heat work FILLBLANK:_____ always increases for isolated systems. Entropy Energy Temperature Pressure FILLBLANK:Process that can reverse with infinitesimal change is _____. reversible irreversible spontaneous non-spontaneous FILLBLANK:Most real processes are _____. irreversible reversible spontaneous endothermic TRUE/FALSE: Exothermic reactions have ΔH < 0. TRUE FALSE TRUE/FALSE: Endothermic reactions have ΔH > 0. TRUE FALSE TRUE/FALSE: All spontaneous reactions are exothermic. TRUE FALSE TRUE/FALSE: Entropy always increases in universe. TRUE FALSE TRUE/FALSE: Gibbs energy G = H - TS. TRUE FALSE TRUE/FALSE: When ΔG = 0, system is at equilibrium. TRUE FALSE TRUE/FALSE: Heat capacity depends on mass and substance. TRUE FALSE TRUE/FALSE: Heat of vaporization equals heat of fusion. TRUE FALSE TRUE/FALSE: Reversible processes are real processes. TRUE FALSE TRUE/FALSE: Hess's Law applies to ΔH only. TRUE FALSE TRUE/FALSE: Spontaneous at all T when ΔH < 0, ΔS > 0. TRUE FALSE TRUE/FALSE: Spontaneous at high T when ΔH > 0, ΔS > 0. TRUE FALSE TRUE/FALSE: Internal energy is only kinetic energy. TRUE FALSE TRUE/FALSE: Work is positive during expansion. TRUE FALSE TRUE/FALSE: Entropy is only disorder in molecules. TRUE FALSE Previous Next Submit Quiz Want to save your progress? Create an account or log in to track your quiz scores! Register/Login