CHEM-100 [Aronson] Quiz 4 (Summer 05)

CHEM-100 [Aronson] Quiz 4 (Summer 05) - Quiz #4, Summer...

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Unformatted text preview: Quiz #4, Summer Term, 2005 Professor C. L. Aronson CHEM 136-09: Principles of Chem. Lab Kettering Unixersity —-- $7 /?, .. acidic“ \LHLT— Name: '1"t'_.'"=._'l -.'| :24, 51;}. -;.r._"-._'[' i- I point per answer U 1 ) A pH below 7.0 is considered (circle best answer): basic- 2) What is the mathematical relationship between pH and [H+]‘? Al'lSWCI'i H = — .I 1'9... ; 3) What is the inverse mathematical relationship between [1-H] and pH from problem #2? Answer: |H+|= I. ' 4) If the pH of an aqueous solution is observed to be 12.9. what is the [IT] ofthe 1 | solution? I_ ,I _ [War— . Answer: 5) Match each ion on the left with the color of the precipitate on the right (using an arrow) from the confirmation tests used in the qualitative analyses you performed last week: Pb+3 BI? Milky White Hg?2 Grey to Black Ag+ M Yellow 6) What volume in mi of a 2.95 molar stock solution is needed in order to prepare 100.0 ml. of 210.0955 molar solution? _ . l . = .._. d Hp—h. a. _ t . I. ": Li I ' ' 1 Answer: as: (“—LI ml 7) The pH meter reads 4.8 for a 0.02 M solution of a weer acid. What is the percent ionization of the acid? \_ _, __,..' d1 1/, Professor C. L. Aronson CHEM l36—09i‘diiiii'it4. Summer Term. 2005 ljage l Answer: ' ) (7- ‘70 ion ionization 8} What numerical value nit/he product (ll-1+] [OI-I'D is equivalent to? Answer: §|H+| |0H'|! = = .' L! 9) What is the pH of a 5.85 M NuOH solution? i0) What is the pH of 3 0.000001 M HCl aqueous solution? Answer: EH = r"- l l ) What is the effect of a buffer? (a) to acceierate changes in 131-! {b} to make pH changes easier to detect (c) to make a solution more acidic (d) to make a solution more basic git-j). to resist changes in pH 12] Group A cations were separated on the basis of their analysis laboratory performed last week. in the qualitative (a) weight Kb) solubility (c) volume (d) size (e) charge /\ Professor C. L. Aronson CHEM 136-09: Quiz #4. Summer Term. 2005 ‘ H “ ' ' - . 2+ + 13) You are given an unknown containing one or more of the three. tons Pb .Ag 1 . . . . . . . . andfor Hgg‘l. Given the toilowrng prospectlve chemical reactions and experimental observations below, identify all the ions present in the unknown solution. (a) Ag+ and Hg;2+ (b) Pb“ and Ag+ @DbIH and Hg22+ Pb3+. Ag and Hg?“ (6) Pb:+ (fl Ag+ Prospective Chemical Reactions: AgCl (s) + 2 NH} ('aq) # Ag(NI-13)2+(aq)+ Cl' PbClg (s) + hot 1-130 {1} = Pb2+ {aq} + 2 Cl’ Hg3Clg is) + 2 NH3 (aq) -——‘ Hg NHgCl (s) + Hg° (l) + NH4+ (an + Cl" (aq) - Pb2+(aq) + KI (aq) —) Pblg (s) Exgert’mental Observations: When HCl is added. a white precipitate forms. Hot water is added and the liquid and remaining solid are separated. Addition of K1 to the liquid phase caused a visible change in the solution to form a bright yellow precipitate. LaJanI-‘ 4. The remaining solid from step 2 is washed twice with hot deionized water. decanted and then finally treated with ammonia ("NI-l3) {aq}. After stirring, there is a visible change in the bottom of the test tube where a gray-black colored precipitate has formed. 5. The liquid was decanted and separated into a test tube. 6. HN03 is added to the supernatant liquid isolated in step 5. No white precipitate was observed to form. Scratch Calculation Area for CHEM 136-09: Summer Term, 2005 Quiz #4 Professor C. L. Aronson Professor C. L. Aronson CHEM 136-09: Quiz #4, Summer Term, 2005 Page 3 ...
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CHEM-100 [Aronson] Quiz 4 (Summer 05) - Quiz #4, Summer...

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