JL alt ctrl ins del NAME SECTION DATE POSTLABORATORY ASSIGNMENT "barium/calcium/magnesium" unknown solution and aqueous (NH4)2SO4 produced a white precipitate that gave a green flame test. After centrifuging and decanting, the addition of aqueous (NH4)2C2O4 produced a white precipitate that gave a brick-red flame test. After centrifuging and decanting, the addition of aqueous Na2HPO4 and NaOH gave no reaction. State the cation(s) confirmed present and absent in the unknown solution. Cation(s) present Cation(s) absent 2. A "barium/calcium/magnesium" unknown solution gave no reaction with aqueous (NH4)2SO4, or aqueous (NH4)2C2O4. Adding aqueous Na2HPO4 and NaOH gave a white precipitate. After dissolving the precipitate in HCI, and adding magnesium reagent, the solution gave a clear blue gel precipitate. State the cation(s) confirmed present and absent in the unknown solution. Cation(s) present Cation(s) absent

2. What concentration of OH is required to begin the precipitation of Cu(OH)2 from a solution containing 0.10 M Cu²+? Ksp for Cu(OH)2 = 2.2 x 10-20. a) 0.20 M b) 1.1 x 10-20 c) 4.7 x 10-10 d) 6.0 x 10-7 e) None of the above JAGill Dl Cl proginitato form?

The concentration of a solution of EDTA was determined by standardizing against a solution of Ca2+ prepared from the primary standard CaCO3. A 0.4302g sample of CaCO3 was transferred to a 60mL volumetric flask, dissolved using a minimum of 6 M HCl solution, and diluted to volume. A 44mL portion of this solution was transferred into a 250-mL Erlenmeyer flask and the pH adjusted by adding 5 mL of a pH 10 NH3-NH4 L buffer containing a small amount of Mg2+ EDTA. After adding calmagite as a visual indicator, the solution was titrated with the EDTA, requiring 632mL to reach the end point. Calculate the molar concentration of the titrant

1. A “barium/calcium/magnesium" unknown solution and aqueous (NH4)2SO4 produced a white precipitate that gave a green flame test. After centrifuging and decanting, the addition of aqueous (NH4)2C204 produced a white precipitate that gave a brick-red flame test. After centrifuging and decanting, the addition of aqueous NazHPO4 and NaOH gave no reaction. State the cation(s) confirmed present and absent in the unknown solution. Cation(s) present Cation(s) absent