Consider the reaction: 4HCl(g) + O₂(g) → 2H₂O(g) + 2Cl2 (9) Using standard absolute entropies at 298 K, calculate the entropy change for the system when 1.69 moles of HCl(g) react at standard conditions.

The decomposition of nitrogen pentoxide in the reaction 2N₂O5 (s)→ 4NO2(g) + O2(g) is endothermic with AH = +110 kJ/mol. Even so, this reaction is spontaneous for temperatures above 230 K because the change of a solid into a gas is a large increase of entropy.

Ice cubes at 0°C are poured into a glass that initially contains 150 g of liquid water at 20°C. The contents of the glass are gently stirred. After a short time, some of the ice melts, and the liquid cools to 0°C. No appreciable heat exchange occurs between matter inside the glass with matter outside the glass during this process. (a) Calculate the entropy change of the universe during the process. Use only the following data: the constant pressure heat capacity of liquid water is approximately 4.18 J/(g K) over the temper- ature range of interest. You may further presume that the density of water is constant over the temperature range. (b) If the same process were performed reversibly, how much useful work would be obtained from it? Any required heat exchange to achieve the same final state reversibly should be with matter outside the glass, which are at 20°C.

Elemental carbon usually exists in one of two forms: graphite or diamond. It is generally believed that diamonds last forever. The table shows the standard enthalpy of formation (AH) and the standard molar entropy (Sº) values for diamond and graphite. Part A AGrxn= What is the standard Gibbs free energy for the transformation of diamond to graphite at 298 K? Cdiamond →Cgraphite Submit Express your answer to three significant figures and include the appropriate units. ► View Available Hint(s) O Substance Cgraphite Cdiamond μA Value AH (kJ/mol) Units 0 1.897 ? S° (J/mol. K) 5.740 2.38

Using the thermodynamic information in the ALEKS Data tab, calculate the standard reaction entropy of the following chemical reaction: CH,OH (g)+CO (g) → HCH,CO₂ (1) Round your answer to zero decimal places. -0 K X

Predict which member of each of the following pairs has the greater standard entropy at 25°C: (a) Sc1s2 or Sc1g2, (b) NH31g2 or NH31aq2, (c) O21g2 or O31g2, (d) C(graphite) or C(diamond). Use Appendix C to find the standardentropy of each substance.

In order to be a spontaneous reaction, what has to be true about Gibbs Free Energy?