Question

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Construct a galvanic cell using the following half-reactions: Cr3+ (aq) + 3e - Cr(s) º = -0.56 V 2 Hg2+(aq) + 2e - H922+(aq) = 0.92 V 2 Ho2+ The initial concentrations are: [Cr3+] =0.31 M [Hg2+] =2.57 M [Hg22+] =0.49 M (1) What is the potential of this non-standard cell at 298 K? Give your answer to 3 sig. figs. E(V) = Submit Answer Tries 0/2 (ii) How will each of the following changes to this cell change its potential? reducing the size of the Cr electrode adding 500 mL of water to the anode Submit Answer Tries 0/2 (iii) Which of the following changes will occur as the reaction proceeds? true The [Hg2+] will decrease true The Cr3+] will decrease true The mass of the Cr electrode will increase Submit Answer Incorrect. Tries 1/2 Previous Tries (iv) How much work can be done by this cell, at 298 K under standard conditions? Give your answer to 3 sig. figs. AGº (kJ) = Submit Answer Tries 0/2

Answer 1

TH 2+ + 2e → Hght E: -0.56v E= 0.924 Reduction of Hat occans & oxidation ! so E. (Ered ca trade + (Eoxidante - 0.92 +10.56) 1.48 V According Eccle - ou to Nernst equation Ecale u - RI en (Product) " nf (Reatant) Total reaction can be written by multiply i by a & (ii) by 3 and subtracting to prom ) 6 Hght + + 200 BHght + 263+ + 6 6 Hght + 26 3 Hg2+ + 20+ 34 oxidation - Reduction Use Alesait equation i Stochionaty أنهينامه F. 96 sto cimol a aut ft R- taraday's constant - 96500 clmol. Gras constant = 8.314 J/kimol

ha T: No. of electrons Temperature exchanged Interchanusting Date: / / E: 1.48 - 8:314 X 298 X 2-203. loz (Hg3 (6) 6 x 96500 = 1.48 - 0-00985 log (6.49² (0.312 12.57" 1:48 -0.00985 log (0:117 x 0-0 288.1 - 1:48 - 0.00985 log (3.9x169) 1.48 to 04 34 Euce - 1.523 v eil) No change We see the size included on full as in reducing size of electone does not depend on he term for size is the Nemet equation On adding 500 ml HO This will decrease the concentration of aq. Gre Hence according to Nessant quation log value decreases love value) i overall Ecce increases.

anodic elechode As reaction proceeds; is consumed cr Cr3+ + 3e- 서 쯔 increase decrease of cr electrode mass decreases AG = nFE - 6 X 96500 X 1.48 - 8 56920 J Ball -85.7 Kuld 2 =