(a) What is the percentage of MnO2 in a pyrolusite ore if a sample weighing 0.4000 g is treated with a 0.6000 g of pure H,C,O4.2H2O and dilute H,SO4 and after reduction has taken place (MnO2 + H2C204 + 2H* → Mn2+ + 2CO2 + 2H,O), the excess oxalic acid requires 26.26 mL of 0.1000 N KMnO4 for titration? (b) If pure As,O, were used instead of oxalic acid, how many grams would be required in order for the other numerical data to remain the same?

If concentration of [CrO4 ] in Expt. 7 is found to be 6.7 x 105 M, what is the experimental Ksp of Ag,CrO4? a) 3.0 x 1013 b) 6.0 x 1013 c) 1.2 x 1012 d) 1.8 x 108 Ksp of Ag.CrO4 = [Ag]° [CrO,?] Ag,CrO4 2 Ag+(aq) + CrO,-(aq), moles, and concentration, of Ag+ are twice those of Cro Ksp of Ag.CrO, = [Ag"] [CrO,] = [2Cro.1°[CrO,] = [CrO.,*]

For (a.) Al3+|Al,  (b.) Cu2+|Cu, (c.) Li+|Li, (d.) Cd2+|Cd, (e.) Au3+|Au Given redox couples, determine the temperature at which the redox couples are in equilibrium considering under standard conditions: 25 °C 1 M concentration for each ion participating in the reaction The partial pressure of 1 atm for each gas that is part of the reaction

1.  A 0.9882 gram sample of iron ore is dissolved, the iron reduced to Fe2+, and the solution was titrated with 36.40 mL of 0.02065 M KMnO4 in acid solution. (a)  Write the titration reaction.  (b)  Calculate the %FeO (M.M. = 71.85) in the sample.   2.  A sample of primary standard grade K2Cr2O7 (MM = 294.20) weighing 0.2153 g is dissolved, the solution acidified and excess KI added. The liberated I2 requires 44.86 mL of the Na2S2O3 for titration. (a)  Write the titration reaction.  (b)  Calculate the molarity of the titrant solution.    Box the final answer.