Analytical chemistry calculations
1. (5 marks) Calculate the solubility product of Hg2SO4 using the following half-reactions: reduction of Hg2SO4(s) to Hg(l) and reduction of Hg22+ to Hg(l).
2. (5 marks) An electrochemical cell is constructed in which both electrodes are made of platinum, but in which one electrode is in contact with an aqueous solution containing [Fe2+]=0.0765M and [Fe3+]=0.176M while the other electrode is in contact with an aqueous solution containing [Ce4+]=0.0376M and [Ce3+]=0.0987M. The two half-cells are connected with a salt bridge of saturated KNO3.What is the potential of this cell at 35.0°C? What is K value for net cell reaction at 35.0°C?
3. (5 marks) Calculate [H+], given the electrochemical cell shown below has an Ecell =1.018 V. The Eo for Fe3+/Fe2+ = 0.771 V and Eo for UO22+/ U4+ = 0.273 V.
Pt(s) | UO22+ (0 .050 M), U4+ (0.050 M), HCO2H (0.1 M), HCO2Na (0.3 M) || Fe3+(0.050 M), Fe2+ (0.025 M) |Pt(s)
4. Calculate the potential of the solution (vs. S.C.E.) in the titration of 50.0 mL of 0.100 M Fe2+ in 1.00M HClO4 with 0.0167 M Cr2O72- at
(a) (4 marks) 10.0 mL titrant added
(b) (2 marks) 25.0 mL titrant added
(c) (4 marks) 49.9 ml titrant added (hint: may need to use an approximation)
(d) (3 marks) 60.0 mL titrant added.
(e) (7 marks) Plot the titration curve using Excel or other spreadsheet software.
(f) (2 marks) What would be a suitable redox indicator for this titration and why?
5. Calculate the potential of the solution (vs. S.C.E.) in the titration of 50.0 mL of 0.100 M Fe2+ in 1.00M HClO4 with 0.100 M Cr2O72- at
(a) (2 marks) 3.0 mL titrant added
(b) (2 marks) 7.0 mL titrant added
(c) (2 marks) 8.40 ml titrant added
(d) (5 marks) Plot the titration curve using Excel or other spreadsheet software. How does the curve compare to the curve obtained in Question 4?
(e) (2 marks) What parameter would you change in redox titration to make the equivalence point easier to detect? Answer the question both in (i) general terms and with specific suggestions for this particular titration.
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