1B-S10-Quiz-5-key341

1B-S10-Quiz-5-key341 - Quiz 5 Chem 1B, Spring 10 \ Fossum...

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Unformatted text preview: Quiz 5 Chem 1B, Spring 10 \ Fossum H3PO4 Kal = 7.5 x 10-3, Ka2 = 6.2 x 10-8, Ka3 = 4.2 x 10'13 NH3 Kb=1.8x10‘5 KW=1.0x10'14 Kabe=Kw 1. 25.0 mL of0.300 MNH3 is titrated with 0.200 MHBr. [030%] c kg m l/2 Mt a. (1) What is the pH at the halfway point in this titration? 7 {AM P (‘0 >40 ‘2“ ' f b IXxw5 +- = Va Jill“ H _, (“30] (ism/x— > (:3, gig kg: 5% X 10'” (HA3 CA a a 0 My .... w b. (2) Determine the pH at the 1/3 of the way point (where 1/3 of the original has reacted). V N03 + M3 0* r-———? on; + I; Q @303 2 {4” ($41.?) afl \l2 4 ((3 0 ) ("a ‘“ V3 _ . f5. .. _, (“30% = EééXlO'M/V}. ._.,. 2/5 Z @ L/‘3 ( = Z.”7<gx(0"° c. (7) Calculate the pH at the equivalence point in this titration. PH : q . ‘5 M “wt, 6,}; MU3 has been CMWIHA +0 Nuzfi @0079 M03 NH; “04th H makers- wmvm an - Mobs vCl 2H WU s “Bf 0 007 a: r QM”, (WNW Jews/>{ ‘ L “1153’ “373 ‘— 0’ 370;“ M5” mas-mt W5 0 00150 m “ 0150M r 0 WC “0" ’r a. LIZO NHS + HJO1 A Hum H > 0075(0wa CZ ‘ 0 , V “L ' 0 007% mi 1300529 magw WWJS all '92. by $04 A MO 0079) g5 cs ooKOrwies Md, U“ 470%; i a . M k . O 5/ , __ ’ NM: 4 a; g5 <5 x: 5’ tax“) (“M H30 i 0 ix 40! (er _ y; K x PH— 5.0q c ova/X ’L 2 " 40 7 K v - , asexio 14a Kn ’ X ’ OJZO 2- l 2. You have 400. mL of a buffer that is 0.10 M in H2PO4' and 0.40 M in HPO4 . g (Age 14132 of ngdq f $.2X lo.— a. (1) What is the pH of this buffer? = 2 0+1 'M [140* : éfZMO-i’O‘lgfljifia‘tp>: (.55 x/o—YM bl (“AHA > 3 1 51% M H1004? [4501‘ “30:3: ‘4“ ( PH‘ 7‘3“, b. (6) What volume of 3.00 M HBr (aq) or 3.00 M KOH (aq) (specify which) would 3e .4 needed to change the pH of this buffer to 7.10? H mus+ eta army, 50 ad? €94 wheat is ‘W (ZUHOOF A'/H,A MWA m W wick-1476,01: 10'?"0~,— 7.51%X‘0'YM _ _ , . --2 _3 - .. mam-1 A,— r x 0.7809: owes A HA 7'44 x [0"? ‘ MHA l’lwu‘ {mam moLzs do wt MAW. “to am [0400-q OAOM. a.” mare Hp‘f (0:4OOL 3: 0,040 Mi (415304 . (/ >: L, 051d Hfif’ will mac-f Will/l4 m ‘3 k Q52! mm Imfl‘er- \430* 4 1490:” I? H2904, "‘ W0 X: mausHBr X OW, We 0.040 mi MK 47) WA 51m . A "X “X, l x . aw} J W to end UP “mm We- _’ ’ 2v O'Ha’z" ‘i’ ’ I — : fog?“ HLPQ X: 0513?- 00723 mam ( HLPOQ 0' (ou0404x)(o.>9§0§} :~ 0.19 "X f I e) 1 2, Her .. 0.025“ t. ‘ v -. —- 3 W {WWW - . \22 ’ (meow - 0 No X (a 0,072 { L‘ feign fit->4 «003122 3‘OOMHgY 24 I” m \ - n i 2 ML \\'\ C- (3) What mass OfNaH2PO4 or NazHPO4 would be needed to chanwe """""""""""""""""" " original buffer to 7.10“? - a e ,_ U fill ci/mmz ‘ mm: but Wh mid w ( “ADO” > “fax/Ne cat/«$6852. {tad—10nd Pd ’ Md Ham’- OID‘lO M Hz {2' ,. _ H907~ mot alum H1504 M205 mot W : 2:9 ____ ........ 1,, , Xmas Him; in W M40 + >< Wm M e Wm a 0 Ho _ 0,15%? Oallob’ M M0? it 0 mos (0M ' up V W’ 0 0911 +03%“ :giogwl (a “753 Natl Po ( m Q9“; WM — mo 3 2 4 f e w0072\21 I 01w“? \M 2a ‘ “film ...
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1B-S10-Quiz-5-key341 - Quiz 5 Chem 1B, Spring 10 \ Fossum...

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