The change in Gibbs free energy is the amount of energy available to do what? pe
ID: 535615 • Letter: T
Question
The change in Gibbs free energy is the amount of energy available to do what? perform work drive the reaction in a forward direction change the entropy of the surroundings heat the surroundings Calculate E for the following reaction at 298 K when [Mg^2+] = 0.400 M and [Na^+] = 0.0100 M: Mg^2+ (aq) + 2 Na (s) rightarrow Mg (s) + 2 Na^+ (aq) +0.404 V +0.357 V +1.203 V -0.722 V +0.309 V Can a voltaic cell in which both half-reactions are the same generate a current? Yes, electrons always flow toward the electrode with the more positive standard reduction potential. No, if there is no difference in standard cell potential between the half-reactions, there can be no driving force for electrons to flow. Yes, if there is a difference in concentration between the two half-reactions. Yes, as long as any two half-cells are connected by a salt bridge, a current will now.Explanation / Answer
Q20. Gibbs free energy is the amount of energy available for a system to do useful work.
Gibbs free energy of system depends on change in enthalpy and entropy at constant T and pressure (dG = dH-TdS)
Q21. Mg^2+ + 2Na -----> 2Na^+ + Mg
The EMF of a cell can be calculated using Nernst equation Ecell = E0cell-(0.0591/n)log[P]/[R]
E0cell = E(Mg^2+/Mg) + Eanode (Na/Na+)
E0cell = -2.714+(-2.363) = 0.351
Ecell = 0.351+(0.0591/2)log((0.010)^2/0.4)
Ecell = 0.404 eV
Q22. No, if there is no potential difference in standard cell potential between the half reactions there is no driving force for the flow of electrons