CHMA11H3 Lecture Notes - Lecture 4: Jmol, Molar Mass, Standard Molar Entropy

The graph on the right shows the chemical potential of two pure gases, A and B, as a function of temperature at the standard pressure of 1 bar. Circle the correct statement the standard molar entropies of A and B are equal to each other at temperature T. the standard molar entropy of substance A is greater than the molar entropy of substance B at temperatures below T_1. the standard molar entropy of substance A is greater than the molar entropy of substance B at temperatures above T_1 the standard molar entropy of substance A is greater than the molar entropy of substance B at all temperatures indicated the standard molar entropy of substance A is smaller than the molar entropy of substance B at all temperatures indicated Gases A and B are mixed and a small amount of catalyst is added to allow the chemical reaction: Circle the statement or statements which are certainly correct (assume gases A and B are ideal gases): At temperature T_1 the standard molar Gibbs free energy of the reaction is zero) At temperature T_1 the reaction is at equilibrium when the partial pressures of A and B are both 1 bar At temperature T_2 the standard molar Gibbs free energy of the reaction is positive At temperature T_2 the standard molar Gibbs free energy of the reaction is negative

3. Which statements below are TRUE for enthalpy and entropy? Enthalpy is the heat flow, q, under constant applied pressure. Standard conditions for entropy and enthalpy changes are 1 M concentration, 1 bar pressure and 298.15 K I II III The entropy change for a system is the amount of energy, at a IV he entropy change for a system is the amount of energy, at a given temperature, that is dispersed into motion of the molecules in the system. When the value of AH is negative, heat is released. When the value of AS is negative, entropy is increased. A) B) C) D) E) I, II and III I, III and IV II and IV III and IV Another combination is true.