chapter6 - Chapter 6 6.6 Write the Nernst equation for? (a)...

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Chapter 6 6.6 Write the Nernst equation for? (a) The reduction of 0 2 ? In general terms, the Nernst equation is given by the formula: Q NF RT E E o ln - = where Q is the reaction quotient. For the reduction of oxygen: O 2 (g) + 4 H + (aq) + 4 e- 2 H 2 O(1) - = = + + 4 2 4 2 ] [ 1 log 2 059 . 0 ] [ 1 H pO V E E H pO Q o Therefore, the potential for O 2 reduction at pH = 7 and p(O 2 ) = 0.20 bar is E = 1.229 V - 0.42 = 0.81 V (b) The reduction of Fe 2 O 3 (s)? For the reduction of solid iron(III) oxide: Fe 2 O 3 (s) + 6 H + (aq) + 6 e - 2 Fe(s) + 3 H 2 O(l) - = = + + 6 6 ] [ 1 log 6 059 . 0 ] [ 1 H V E E H Q o since pH = -log[H + ] = -2.3ln[H + ] and log[H + ] 6 = 6log[H + ]. ) ( 8 . 13 6 059 . 0 ] [ 1 6 pH V E E H Q o - = = +
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6.8 Using Frost diagrams? (a) What happens when Cl 2 is dissolved in aqueous basic solution? The Frost diagram for chlorine in basic solution is shown in Figure 6.16 and is reproduced below. If the points for Cl - and ClO 4 - are connected by a straight line, Cl 2 lies above it. Therefore, Cl 2 is thermodynamically susceptible to disproportionation to Cl - and C1O 4 - when it is dissolved in aqueous base. In practice, the oxidation of ClO - is slow, so a solution of Cl - and ClO - is formed when Cl 2 is dissolved in aqueous base. (b) What happens when Cl 2 is dissolved in aqueous acid solution? The Frost diagram for chlorine in acidic solution is shown in Figure 6.16. If the points for C1 - and any positive oxidation state of chlorine are connected by a straight line, the point for Cl 2 lies below it (if only slightly). Therefore, Cl
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chapter6 - Chapter 6 6.6 Write the Nernst equation for? (a)...

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