Question

Prelab Activity:

Electrochemical Cells

1. To determine the solubility product of copper(II) carbonate, CuCO₃ , a concentration cell as described on pages 71-72 of the lab handout is constructed. The temperature of the Galvanic cell is measured to be 22.5°C, and the cell potential 282 mV (0.282 V). Using this data and Equation 8 in the lab manual, calculate the K_sp for CuCO₃ and report your answer with three significant digits.

2. For the Galvanic cell you will construct in PART B, the Nernst equation may be written as follows:

Ecell=E^°cell-RTnFln[Zn²⁺ ] (aq)[Cu²⁺ ] (aq)

Assuming the cell temperature remains constant, if the concentration of Cu²⁺ (aq) in solution is decreased, is the measured cell potential ( E_cell ) expected to increase or decrease?

3. What function is served by the 1 M KNO₃ solution used in this experiment?

Answer 1

given . Ecell = 0.282v T = 22.5°C - (22.5+ 273)k = 295.5k 1 ksp for Cuco, = ? cell reaction Cu (s) + cut (concentrated) - Cu(s) + Cut ilute) +2 E cell = 0 Nernst equation for this cell can be written as it E cell = o-RI en kop ne n=a T = 295.55 R = 8.314 Jkt molt f = 96500 cmolt X 2.30 Ecell = o- RI x 2.303 log kup = - NF 1x 95.5 x 2.303 log tsp -8.314 x 295.5x2.303 0.282 V : 2 x 96500 log kup = -9.619 kep = 2.40 10-10 TBS PART B E cell = Ecell - RT en [ant] (Cutz] ne . when term we decrease [zne will [cu*] concentration of cutz ions ie (cuty increase. so en (antry will increase B (cute] is 2 to be subtracted from which R RT en [znt I nF Leute will increase E cell Hence Ecell will decrease. • Role of IM KNO₃ equal KNO₃ is a lil electrolyte which have transport number for cation & anion (ie t = t_) this it act as a salt Bridge. functions: it It faciliate transfer of charge. jiy It completes the circuit.