# Exam 1 – Pollard

 The enthalpy is ________ when a A-A reactants form A-B products.
 negative
 The entropy is ______ when there are more moles of gas on the reactant side than product side.
 negative
 What are the 3 things to look for when determining entropy?
 1. moles of gas (which side has more?)2. complexity of products/reactants3. size/mass of compounds
 The enthalpy is ___________ when A-B reactants for A-A products.
 positive
 The entropy is ___________ when a complex/larger reactant forms a simpler/smaller product.
 negative
 The enthalpy is ____________ when breaking ionic compounds.
 positive
 The entropy is ___________ when the reactants form gaseous products.
 positive
 If a chemical reaction results in ONLY a phase change, do the enthalpy and entropy have the same or opposing signs?
 Same.
 How do you find the percent yield of a reaction?
 (experimental yield/theoretical yield) X 100
 A reaction is spontaneous when its change in Gibbs free energy is ___________.
 negative
 A bond is _______ and less stable when it has _______ potential energy.
 weak; high
 Breaking bonds __________ energy while forming bonds ________ energy.
 requires; releases
 Exothermic processes are ________ energetically stable.
 more
 The ________ stable the products, the more likely the reaction to proceed to ___________. (____________)
 more; completion; extent
 If the enthalpy is negative, then the process is ___________.
 exothermic
 Exothermic processes energetically favor _________.
 products
 If the enthalpy is positive, then the process is ____________.
 endothermic
 Endothermic processes favor _____________.
 reactants
 The stronger the intermolecular forces, the more ____________ the enthalpy.
 negative
 Based on Coulomb’s Law, one may expect forces between ions to be stronger in these 2 scenarios:
 1. the larger the charge of the ions (larger q’s)2. the smaller the size of the ions (smaller r)
 The higher the entropy, the ________ configurations in a system.
 more
 A phase change goes from solid to liquid, from liquid to gas. Thus, the process is ____________.
 endothermic
 A phase change goes from a gas to liquid, from a liquid to solid. Thus, the process is ____________.
 exothermic
 Chemical reactions in which the total entropy of the products is higher than the total entropy of the reactants are entropically __________.
 favored
 These 3 descriptions point towards a reaction that is entropically favored (entropy > 0).
 1. fewer constraints2. larger molar mass3. more complexity
 ___________ are dominant factors for entropy.
 Gases
 Is favorability of a reaction temperature controlled?
 No.
 The more negative the Gibbs free energy is, the __________ the extent of the reaction and the more thermodynamically stable the ___________ than the ____________.
 larger; products; reactants
 What is the Gibbs free energy equation?
 G = H – TS
 What is the 2nd Law of Thermodynamics?
 At constant T and P, G < 0 for thermodynamically favored processes.
 The Gibbs free energy equates to ____ for elements in their standard state.
 0
 Chemical reactions tend to reach an ______________________ in which the concentration of products and reactants does not vary over time.
 equilibrium state
 Product-favored process: G < 0, K ___ 1Reactant-favored process: G > 0, K ____ 1
 >; <
x

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