Question

1. Suppose you are given an unknown aqueous solution that contained one of the following cations AR', Ba", or Na'lons. You have available the following test solutions: 1 M sulfuric acid and 1 M hydrochloric acid. Explain how you would use these test solutions to determine the identity of the cation in the unknown solution. Using complete sentences and proper terms, explain the tests you would perform, the expected outcomes, and how the results would allow you to determine the presence or absence of each particular cation. 2. The ions A, B, and Call form colorless aqueous solutions. Their molecular counterparts, however, form brilliantly colored solutions, where A, is green, B, is blue, and C, is red. When a student mixes the anions C and A with a solution of B, the following results were obtained: i) B2 + 2C → red solution (B oxidized C to C) ii) B2+2 A blue solution (B does not oxidize A to A2) a) Rank A, B, and C, in order of increasing oxidizing strength. b) Would the following reaction occur? Az + 2C → C2 + 2A Explain why or why not. c) Devise a single-step test that one could use to analyze an unknown solution containing one of the three anions: A, B, or C using either A, B, or Cas a test solution. Explain how and why this would work. Rev. 518 Page 1 of 6

Answer 1

0 Agt cags react with a (aq) to form curdy white Precipitate of Agd. Batt(aq) react with so = (aq) to form heavy white Precipitate of BaSO4. Nat solution neither precipitate as Nach nor Na,soa a sample + Sample + few drops of the white precipitate. - then solution contains Ag+ (aq), few drops of Ho sog white precipitate - then solution Contains Bat (aq), few drops of Hell or Hasoa No Precipitate then Nat (aa) present, Sample + ② I Agt caq) + ci caq, Agdley Battcaq) + Sozi caq) → Basoq (s) @ Aj Bi í form colourless solution, Aż Green ; By ~ Blue ; Cg > Red, B2 +26 - QB +Cg Be is more onidishing agent than Ca B₂ + 24 > 2B²+ Az 2. B2 is lese oxidising agent than A2 Increasing order of onidising etrength - Az> BzZla -

o As A is strongest ozudising agent among the three onidising agents, so, Ag will onidése Cą to Cq. and the colour of the solution becomes red, C Green Red A +26- 2A to Blue @ As Ae Can onudised both B & c- there for Aa can be used to identify the unknown solution of Am, Bies The followsing Procedure can be used, Sample t A Red Solution a Colourless Green co-present, Ag +2c" > 2A + Cg Blue, Red, Green Sample + A2 Blue Solution , B- Present, A2+28 > 2A+ Bg - Green Вале , Sample + A2 1 s > No colour change A- Present No reaction . Az ta Green. Green