Exam2_1_S2004

# Exam2_1_S2004 - How many mL of 0.01 M HCl must be added to...

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Exam #2 Chemistry 112 Spring 2004 Name: __________________________________ Social Security Number: ___________________ For ALL pH questions, express the answer to 2 decimal places !!! Write neatly !!! Show all work !!! [H 3 O + ][OH - ] = 1 x 10 -14 = k w pH + pOH = 14 = pk w pH = - log[H 3 O + ] [H 3 O + ] = 10 - pH pOH = - log[OH - ] [OH - ] = 10 - pOH [HA] ] ][A O [H k 3 a + = ] [A ] [HA][OH [BOH] ] ][OH [B k b + = or k a k b = k w pk a + pk b = pk w pH = pk a + log n b n a = a b a C C log pk + ay 2 + by + c = 0 y = b ± b 2 4ac 2a 1

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1. (10 points) List the following solutions in the order from most acidic to most basic: 0.5 M KCl 0.1 M HI 0.18 M CH 3 COONa 0.45 M Ca(OH) 2 0.217 M NH 4 Br 2
2. (10 points) Calculate the pH of a mixture of 20 mL of 0.4 M KOH and 30 mL of 0.15 M CH 3 COOH. K a (CH 3 COOH) = 1.8×10 -5 . 3

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3. (10 points) How many grams of dry NaOH must be added to 200 mL of 0.4 M H 2 SO 4 to neutralize it completely? Molar mass of NaOH is 40 g/mol. 4
4. (10 points) CN- is a weak base with K b =1.39×10 -5 (it is also a very strong poison). Your job is to prepare a neutral solution with this ion.

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Unformatted text preview: How many mL of 0.01 M HCl must be added to 10 mL of 0.02M of KCN to make a pH = 7 solution? 5 5. (10 points) Calculate the pOH of 0.02 M solution of HOCl, its K a =3.0×10-8 . 6 6. (50 points) Titration: This is a multi-step problem. Calculate the pH for the titration of 20 mL of 0.20 M HCOOH, K a = 1.8 x 10-4 , with 0.1 M LiOH. a) (11 points) Before any base is added. b) (13 points) After 20 mL of base is added. c) (13 points) After 40 mL of base is added d) (13 points) After 60 mL of base is added a) 0 mL of LiOH have been added 7 b) 20 mL of LiOH have been added 8 c) 40 mL of LiOH have been added 9 d) 60 mL of LiOH have been added 10 9. (15 challenge bonus points). Calculate the pH of a mixture of 100 mL of 0.2 M H 3 PO 4 with 50 mL of 1.0 M NaOH. For phosphoric acid K a1 = 7.5 x 10-3 , K a2 = 6.2 x 10-8 , K a3 = 2.2 x 10-13 . 11...
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## This note was uploaded on 10/03/2011 for the course CHEM 112 taught by Professor Chen during the Spring '09 term at South Carolina.

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Exam2_1_S2004 - How many mL of 0.01 M HCl must be added to...

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