15. Victoria added 6 M HCI to a sample of the unknown, containing at least one of the Group I cations. A large amount of light-colored precipitate formed. The precipitate was separated from the supernatant liquid and was found to be insoluble in hot water. The colorless supernatant liquid was separated from the precipitate and after cooling and adding K2CRO4, no precipitate resulted. The separated precipitate dissolved completely after adding 6M NH3. A white precipitate was formed, upon addition of 6M HNO3. What cation(s) may be present in the sample? a. Pb2+ b. Ag* c. Hg,2+ d. Ag*, Hg22* e. Pb2", Ag*

2. After dissolving the KHP with water, a student noticed some undissolved solid, but continued with the titration as instructed by the procedure. He titrated until the pink color persisted for 30 sec and recorded the volume of titrant required. Preparing for the second determination, he set the reaction solution aside and added some more NaOH to the buret. He was about to pour the reaction solution down the drain, so he could rinse and reuse the flask, when he saw that the pink color had disappeared! a) What happened? b) What can the student do to correct for this erTor and salvage this trial? How should the data sheet be modified to reflect this correction? 3. Another student began adding titrant to the acid solution, but stopped when she suddenly realized that she forgot to add the 3 drops of phenolphthalein. When she did, the solution immediately turned dark red! a) What happened? b) What can the student do to correct for this error and salvage this trial? How should the data sheet…

ou are tasked with determining a way to identify the following ions in solution: Na+, Ni2+, Ag+, and Pb2+. What techniques would you use to selectively precipitate out the ions and how would you separate the precipitates from the supernatant layers? Your arsenal of compounds to use for the separation is KCl, KCH3COO, and KOH. Clearly define each step.

The formula H₂SO4 + 2 KOH --> K₂SO4 + 2 H₂O describes the reaction between sulfuric acid and potassium hydroxide. In the titration done, 20 mL of KOH with an unknown concentration is put into a flask with bromthymol blue indicator. The KOH solution was titrated with a 0.25 M H₂SO4 solution. Three trials were performed and each trial yielded to an endpoint of yellow-colored solution, which is the desired endpoint. After three trials, the following readings were obtained: 15.5, 15.1, and 14.9 mL respectively. Calculate the molarity of Potassium hydroxide. (Answer must be rounded off to 2 decimal places)

I titrate a 5.00mL aliquot of Arsenic acid with 36.09 mL 0.126M sodium hydroxide. Calculate the molarity of the arsenic acid sample.

A solution containing 0.13 M each of I− , Br− , CO2−3 , and C2O2−4 is titrated by a solution containing Pb2+ . Place the anions in the order in which they will precipitate. Consulting a table of Ksp values may be helpful.

A pipette is used to add 41 mL of 0.2 M Pb(NO3)2 to a 268.0 mL solution of 0.2 M NaF. Determine the equilibrium concentration of Pb2+(aq) in the final solution. Ksp(PbF2)=3.6E-8Include at least 3 significant figures in your answer.

An alkaline earth hydroxide, M(OH)2, was taken to lab for analysis. The unknown powder was poured into a flask and swirled in room temperature DI water until a saturated solution formed. This solution was then slowly filtered to remove the undissolved solid hydroxide. 11.9 mL of this saturated solution was titrated with 0.148 M HCI (ag). Endpoint required 15.6 mL of the HCl (ag) solution. Calculate the Kan for this alkaline earth hydroxide.

Please answer questions 3a&b based on the information in question 2.

A student was asked to identify a compound. In an effort to do so, he first dissolved the compound in water. He found that no precipitate formed when hydrochloric acid was added, but when H2S was bubbled into this acidic solution, a precipitate formed. Which one of the following could be the precipitate? NiS AgCl HgS BaS