AAMC FL 4 Test Questions & Answers | 115 Questions with 100% Correct Answers | Updated & Verified | 44 Pages

Limestone does NOT decompose when heated to 900 K because, at 900 K, ΔH is: A. Positive and less than TΔS B. Positive and greater than TΔS C. Negative and less than TΔS D. Negative and greater than TΔS - ANS - B. The reaction does not occur (is not spontaneous). This indicates that the ΔG =ΔH-TΔS 0. From inspection of the reaction, it can be concluded that ΔS0. Consequently, ΔHTΔS explains why the reaction does not occur When limestone is heated during Step 1, an equilibrium is established. Which of the following expressions is the equilibrium constant for the decomposition of limestone? A. [CaO] B. [CaCO3] C. [CO2] D. [CaO] x [CaCO3] - ANS - C. From the law of mass action, an equilibrium constant expression involves a ration of products to reactants with exponents determined from the stoichiometry of the reaction. Furthermore, solids are excluded from equilibrium constant expressions. CO2 (g), as the only non-solid material in the reaction, is the only substance that appears in the equilibrium constant expression. During Reaction 2, did the oxidation state of N change? A. Yes; it changed from -3 to -4 B. Yes; it changed from 0 to +1 C. No; it remained at -3 D. No; it remained at +1 - ANS - C.The part of the Reaction 2 that involves nitrogen is the protonation of ammonia (NH3 + H-- NH4+). Acid-base reactions doe not involve oxidation state changes. Furthermore the oxidation states of N in NH3 is -3 not 0.