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(5 pts.) 1. Draw a typical strong acid-strong base titration curve, labeling the axes and the equivalence point.

(7 pts.) 2. Draw a typical diprotic weak acid-strong base titration curve, labeling the axes, the equivalence points and the buffer regions.

(6 pts.) 3. Give the mass balance equation for carbonic acid, H₂CO₃, in a diprotic weak acid-strong base titration.

C_T = [H₂CO₃] + [HCO₃^-1] + [CO₃^-2]

(5 pts.) 4. Give the charge balance equation for the a solution containing H⁺, OH^-, Ca⁺², HCO₃^-, CO₃^-2, Ca(HCO₃)⁺, Ca(OH)⁺, K⁺, and ClO₄^-.

[H⁺] + 2[Ca⁺²] + [Ca(HCO₃)⁺] + [Ca(OH)⁺] + [K⁺] = [OH^-] + [HCO₃^-] + 2[CO₃^-2] + [ClO₄^-]

(4 pts.) 5. In the compleximetric titration of Ca⁺² with EDTA anion, which is the Lewis acid and which is Lewis base.

Ca⁺² is the Lewis acid

EDTA anion is the Lewis base.

(4 pts.) 6. Balance the following redox equation:

6Fe⁺²  +   Cr₂O₇^-2  +   14H⁺  <=>   6Fe⁺³  +   2Cr⁺³  +   7H₂O

(4 pts.) 7. Describe the difference between the end-point and the equivalence-point of a titration.

The end-point is when a physical change, such as change in color of indicator, takes place. This can indicate the equivalence point of a titration if the correct indicator is selected.

The equivalence point is the condition in a titration where the amount of analyte equals, reactivity wise, the amount of titrant added. Determining this point is the point of the titration.

(2 pts.) 8. What is the indicator in the titration of Fe⁺² with MnO₄^-1.

excess titrant

Name ______________________

9. Derive the titration curve for the titration of 25.00 mL of 0.200 M HCl with 0.100 M NaOH.

(3 pts.) (a.) At 0.00 mL of NaOH added

pH = - log([H⁺] = - log (0.200) = 0.698

(4 pts.) (b.) At 25.00 mL of NaOH added, V_aM_a> V_bM_b

[H⁺] = ((V_aM_a) - (V_bM_b))/(V_a + V_b)

[H⁺] = (((25.00mL)(0.200 M)) - ((25.00mL)(0.100M)))/(25.00mL + 25.00mL) = 0.050M

pH = - log([H⁺] = - log (0.050) = 1.301

(2 pts.) (c.) At 50.00 mL of NaOH added, V_aM_a= V_bM_b

The equivalence point of a strong acid - strong base titration, pH = 7.0000

(5 pts.) (d.) At 80.00 mL of NaOH added, V_bM_b > V_aM_a

[OH^-] = ((V_bM_b) - (V_aM_a))/(V_a + V_b)

[OH^-] = (((80.00mL)(0.100 M)) - ((25.00mL)(0.200M)))/(25.00mL + 80.00mL) = 0.048M

pOH = - log([OH^-] = - log (0.048) = 1.322

pH = 14.00 - pOH = 14.00 - 1.322 = 12.68

(2 pts.) 10. Select an appropriate indicator for the titration in Problem 9.

(2 pts.) 11. What is the minimum pH for an EDTA titration for Fe⁺³.

(18 pts.) 12. Using the 9 step procedure, calculate solubility of CuS in water.

(10 pts.) 13. Calculate the pFe at the equivalence point for the titration of Fe⁺² with EDTA at pH = 5.  Assume the Fe +2 ion concentration and the EDTA^-4 ion concentration are both 0.0500M.  The volume of Fe +2 ion solution is 50.0 mL.

14. Derive the titration curve for the titration of 50.00 mL of 0.1200 M benzoic acid with 0.1200 M NaOH.

(5 pts.) (a.) At 0.00 mL of NaOH added

(8 pts.) (b.) At 25.00 mL of NaOH added

(6 pts.) (c.) At 45.00 mL of NaOH added

Under construction

I neither received nor gave any assistance on this examination nor did I see anyone else give or receive assistance on this examination.

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