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exercise 3(answer)

By Carl Brooks,2014-05-03 18:19
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exercise 3(answer)

    Analytical Chemistry (Bilingual)

    Exercise for Chap. 5

Name:____________ No._______________ Class____________

    1. Which of the following could be used as the primary standard? ( D ) A. KMnO B.NHCO C. HCl D. KCrO 4423227

    2. Which one of the following is a pair of conjugate acid and base? ( B ) 2- 2-3- 2-A. HCOCO B. HPOPO C. HPOHPO D. NH-NH.HO 23344344332

    3 A series of solutions containing NaOH, NaCO, and NaHCO alone or in compatible combination, 233

    was titrated with HCl. The volume of HCl needed to titrate the solution to a phenolphthalein end point

    is VmL. Continuing to titrate the solution to a bromocresol green end point needed VmL. If 2V=V12 12, the component of the mixture is _____________ ( B ) ANaOH+NaCO BNaCO+NaHCO 23233

    CNaOH+NaHCODNaOH+NaCO+NaHCO. 3 233

    4. You are titrating a weak base, CHNH, with 0.05000 M HCl. If you start with 25.00 mL of 0.1000 32

    M base, what will be the best indicator (pick from those listed below) to detect the end point? K = b-4 4.35 10( B )Indicator pKa A. Bromocresol Green 4.66

    B. Bromocresol Purple 6.12

    C. Phenol Red 7.81

    D. Phenolphthalein 9.4

    E. None of these

    5. In a solution containing 0.10 mol / L AgNO and 0.20 mol /L NHwhich of the material balance 33

    equation for NH is correct ( D ) 3++A. [ NH ] + [ Ag(NH) ] + [ Ag(NH) ] = 0.20 3332++B. [ Ag(NH) ] + [ Ag(NH) ] = 0.20 332+C. [ NH ] + 2[ Ag(NH) ] = 0.20 332++D. [ NH ] + [ Ag(NH) ] + 2[ Ag(NH) ] = 0.20 3332

    6. Which acid can be accurately titrated with 0.1 M NaOH by direct titration? A

    A. 0.1 M of HCOOH (pK= 3.45) B. 0.1 M of HBO (pK = 9.22) a33a

    C 0.1 M of NHNO (pK = 4.74) D.0.1 M of HAsO (pK = 9.24) 43b33a

    7. The ~of HPOis 2.12, 7.20 and 12.4, respectively. Which statement in the following pKpK34 aa13

    is correct when the pH of HPOsolution is 7.80? ( B ) 34 -2-2-- A. [HPO]>[ HPO] B. [ HPO] >[HPO] 244424-2-3-2-C. [HPO]=[ HPO] D. [ PO]>[ HPO] 24444

    8. The pH of 0.10 mol/L NaA solution is ( C ) (pK=3.90,pK=6.00,pK=10.02) 3a1a2a3

    A. 8.01 B. 10.02 C. 11.51 D. 12.51 2-.-19 The distribution fraction(分布分数) of HY in cmolLEDTA solution is A 22-2-4-4-A. [HY] / c B. c / [HY] C. c/[Y] D. [Y] / c 22.10. NaCOor Borax (NaBO10HO) is used to standardize HCl solution. If NaCO absorbs water, 23 247223

    the result is ___偏高__ And if partial of the crystal water in Borax was lost, the result is __偏低__..?以上两项填无影响,偏高或偏低?___ NaBO10HO ___ is better for primary standard if both 2472

    of them were well stored, because__硼砂具有较大的摩尔质量,可以减小称量误差 .11. The primary standards for the standardization of HCl are__ NaCO__and__ NaBO10HO 232472._____, for the standardization of NaOH is _邻苯二甲酸氢钾_and__HCO2HO _________. 2242-112. Please write down the proton-balance equation of c mol.L NHHPO aqueous 424;23solution [H];[HPO][NH];[HPO];2[PO];[OH]34344

    Attentions: there are three calculating problem need to do in the book of PPT, look

    at the end of chapter 5, you should do at the back of this paper and hands up.

    Analytical Chemistry (Bilingual)

     M(NaOH)=40.01 M(NaCO)=105.99 M(NaHCO)=84.01 233

    (a) V=V, 组成为NaOH PB330.119821.361040.0110 c(NaOH)4095 ppm325.0010

    (b) 2V<V, 组成为NaCO, NaHCO. PB233330.11985.6710105.9910????3c(NaCO)2.8810 ppm???23325.0010 330.1198(21.1325.67)1084.0110?;????c(NaHCO)3941 ppm??3325.0010

    (c) V=0,V>0, 组成为NaHCOPB3 330.119814.281084.0110 c(NaHCO)5749 ppm3325.0010

    (d) 2V=V, 组成为NaCOPB23 330.119817.1210105.9910 c(NaCO)8695 ppm23325.0010

    (e) 2V>V, 组成为NaOH, NaCOPB23 330.1198(221.3625.69)1040.0110 c(NaOH)3265 ppm325.0010330.1198(25.6921.36)10105.9910c(NaCO)2230 ppm 23325.0010

Analytical Chemistry (Bilingual)

3-2-(a) 2V<V, 组成为PO, HPO PM4430.119811.54103--1c(PO)0.05530 molL4325.0010 30.1198(35.29211.54)102--1c(HPO)0.05851 molL4325.0010 (b) V=2V, 组成为 HPOPM3430.11989.8910??-1 c(HPO)0.04739 molL??,34325.0010

(c) V=V, 组成为NaOH PM30.119822.7610-1 c(NaOH)0.1091 molL325.00102-(d) V>2V, 组成为HPO, HPO PM342430.119817.4810-1c(HPO)0.08376 molL34325.0010 30.1198(39.42217.48)102--1c(HPO)0.0214 molL24325.0010

Analytical Chemistry (Bilingual)

3(50.000.0955237.840.05992)1014.01 Protein%100%15.60%1.284617.54%

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