Question

15) (5 pts) equilibrium information below: Calculate the initial pH of the solution given the following reaction and Ca(OH)2(s) Ca+(aq) +20H-(ag) with Kso 1.3 x 105 A) 12.1 B) 11.8 C) 10.3 D) 8.2 E) None of these choices are correct 2x 13x6 (x) 2. 6.3x106 (x) 2 -0.0036 -10002 0.0072 16) (5 pts) How many moles of sodium acetate (conjugate base) must be added to 500.0 mL of 0.100 M acetic acid to produce a solution with a pH of 6.95? (The pK, of acetic acid is 4.74) A) 0.0003 moles B) 0.05 moles C) 0.81 moles D) 8.11 moles E) 81.09 moles 17) (5 pts) Calculate the pH of a solution that is 0.25 M in ammonia (NH3) and 0.60 M in ammonium chloride, given the ionization constant of the base, Kb, NH3 1.76 x 10, and the equilibrium reaction: RNH3 (aq) + H20 () O.25 NHa (aq) +OH (aq) A) 9.63 B) 9.50 C 9.25 D) 8.87 E) 5.13 18) (5 pts) By far the most important buffer for maintaining acid-base balance in the blood is the carbonic acid-bicarbonate buffer. Ka=7.94 x10 H2CO3 (aq)+ H2O (I) HCO3+ H30* To simulate the pH of skeletal muscles, which is approximately 7.2, a solution made by dissolving carbonic acid and sodium bicarbonate together in an aqueous solution. What mole ratio of NAHCO3/H2CO3 is required to produce a solution with a pH of 7.2? A) 12.6 B) 10.0 C) 1.1 D) 0.1 E 0.08

What is the answer to question 15, 16, 17 and 18, and also how did you calculate it

Answer 1

Calon)2 e20)ksp 1-3M16 15) S 2S CaloH) Maring luble Aalt. Let its olubi it be s' mol/ut .then in eavilibsium, s mol of Clon) ditolved to generade s mod f et and 2s mol of H ows Exprassion for Ksp caon) Ksp ea.[5 S. (25) 6the Problem, 4s33x10 /3 4s 3 3x10 4 -3 S68 x 1o . oH ion eoneentration In the Aolution 6.87 0 (M). 6.87 A16) - 2.16 PH-4- 2.16 - 84. aPHtPoH214 The PH of ha olution 8 (opton-8)

16) Henderson-Haselbaleh equahion for tho acidie buffer lem PHPKA t Lsalt Caid for PH- Pka t ertsearoa eoneentration CHeooHmolOsz eon centration Here Ec 0.L (M) 00 mL 0.1 (M) CesoH k preent. We osume that x moleg of et coNa ia added to 5 0D mL Soluion Contaiwi molei C coD Na. . The Coneenbration 6 e CuoNa 500 Now, PHz 6,95, PKa - 4.74 6.95 44 (2x) O.L 6.95-4.74 2. 21 AA:-OPton-D) O, o 0.12-21 or, x)2-21+ o 0.1 L 21 16.22 . 8.11moles of Ceoo Na Rave to be added to getpH=6.95 16.22 8.1 2

0.2 5(M) N and 0.60() NH eonbainolutin Atem Hendaron -Hael baleh eguation for bone bulfer yem salt] Laare 17) tA basie- bufar AallfHe0.60( baseN .25 pot PKbt and PK-lko -l7(1.76x165) . PKo for Nr 4.75 0.60 fmy o.25 POH A.5 5.13 A.T5 0.38 = Aain PHt poH- 14 : PH 14-Po 14-5.13 8.87 en t he Solutton eon tai vi 0.25 ( NMS and 6.60(M) st N c 8.87. (0Phon-D) 18) H2co3-NaH e03 s acidie bufferi galem. H2Co3 Weak acid& ts eorrenpondinhalt ia NaHCO3 Ka .94 xo . Pka 6.10

From Hendarson-tassel bal eh eaahon PHPKatog [NaHco TH2C03 2 6.1 H2e3 NaHco3 H2coz] [Naнеоз 7.2-6.12 4258 2:6 The mole ratio ophon- A) 12.6 (Nat e032c03) 9uired to Produee a Roluti on with PH27.2