1. Consider the process of a solid precipitating out of solution, such as the following equilibrium. This reaction has a very large equilibrium constant, meaning the equilibrium favors the solid product. Ag(aq) Cl-(aq)ââ AgCl(s) K=5.6x 10% + a. Do you think the entropy of this system increases or decreases as the reaction proceeds to the right? b. Explain what happens to the entropy of the surrounding water molecules when AgCI(s) spontaneously precipitates c. Enthalpy (H) can be thought of as a quantification of the potential energy stored in the bonds and IMFs presemt in the chemicals in the system. What kinds of bonds or IMFs are broken in this process? What kinds of bonds or IMFs are formed in this process? d. How is the free energy change of a reaction related to the enthalpy and entropy change for that reaction?
Answer the following questions assuming that 1 mol of formaldehyde molecules are formed.
1. What is the change in enthalpy of this reaction? ÎH = ____ kJ
Does this change in enthalpy represent energy that must be added to the system, or energy that is released from the system? -Energy must be added or Energy is released?
2. What is the change in entropy for this reaction? ÎS = ____ kJ/K
Does the entropy increase or decrease? -Entropy increases or Entropy decreases?
At 298 K, what is the heat transfer that corresponds to this change in entropy? Q = ____ kJ Does this heat transfer represent energy that is added to the system, or energy that is released from the system? --Energy is added Energy is released ?
3. What is the change in Gibbs free energy for this reaction? ÎG = _____ kJ
The Gibbs free energies of formation, ÎGf, are: -228.57 kJ for water; -394.36 kJ for CO2; and 0 kJ for O2. What is the Gibbs free energy of formation for formaldehyde? ÎGf (formaldehyde) = _______ kJ
4. Using the formation of formaldehyde as a model, comment on photosynthesis and the formation of sugars using what we know about entropy and free energy.