Question

(a) Choose all of the statements from below which correctly describe issues pertaining to the relationship between the emf of a reaction and its Gibbs free energy change. The Gibbs free energy change and emf values of a reaction have opposite algebraic signs (+ VS.-). Electron stoichiometry need not be used to interconvert a Gibbs free energy change and a reaction emf. A spontaneous reaction has a negative Gibbs free energy change and a positive emf. A coulomb of particles is more particles than a mole of particles. Electron stoichiometry must be used to interconvert a Gibbs free energy change and a reaction emf. Calculate the standard Gibbs free energy changes at 25 °C for each of the reactions shown below using the Eº values given. Select whether each of these reactions is nonspontaneous, at equilibrium, ar spontaneous under standard conditions. Eº - 0.925 V AGº = kJ/mol (a) 1 Hg2+ (aq) + 1 Sn(s) = 2 Hg(0) + 1 Sn2+ (aq) nonspontaneous O at equilibrium spontaneous E° - 2.891 V AGⓇ = kJ/mol (b) 2 Cul(aq) + 1 Mg(s) = 2 Cu(s) + 1 Mg2+ (aq) nonspontaneous at equilibrium spontaneous

Answer 1

- Key point to remember. it DG 0 [lie af equilibrium] j oG>0 [ie nm- Spontaneous ] jj 04 <o Tre Spontaneous ] (a) Since; s = onfe [n= number of elechons involved] $6.-2796500 C x 0.925V = -178.525 kJ/mol C Spengeneous) molt ob Since; Doº --NFE $40: -2x96500 Cmol'x 2.891 V = -557.963kJ/mol (spontaneous) (c) Since; su =- nf€ Bu = -2%96500 (mut'x 2.773 v a-535.189 kJ/mol Espontaneous) (d) Since ; $(*=-1FE" AG= -2496500 C mol'x -0.030 V = 5.790 kJ/mol (non-sburlaneous )