Homework 07 - ycs73 Homework 7 Fakhreddine (53605) 1 This...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ycs73 Homework 7 Fakhreddine (53605) 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 1.0 points Some solid NH 4 Cl is added to a water solution of NH 3 . Which of the following statements is correct? 1. [OH- ] of the solution increases. 2. pH of the solution increases. 3. pH of the solution decreases. correct 4. [H 3 O + ] of the solution remains the same. Explanation: 002 1.0 points Some solid KClO 2 is added to a water solution of HClO 2 . Which of the following statements is correct? 1. [H 3 O + ] will remain the same. 2. pH of the solution decreases. 3. [OH- ] of the solution decreases. 4. pH of the solution increases. correct Explanation: 003 1.0 points Calculate the pH of a solution containing 0.10 M CH 3 COOH and 0.10 M NaCH 3 COO. 1. 5.78 2. 7.12 3. 8.27 4. 4.74 correct 5. 2.89 Explanation: [CH 3 COOH] = 0 . 10 M K a = 1 . 8 10- 5 [CH 3 COO- ] = 0 . 10 M This is an acetate buffer in which [CH 3 COOH] = [CH 3 COO- ], so pH = p K a =- log(1 . 8 10- 5 ) = 4 . 74473 004 1.0 points A solution that is 0.20 M in NH 3 is also 0.30 M in NH 4 Cl. What is the [OH- ] in this solution? 1. 1 . 2 10- 5 M correct 2. 2 . 4 10- 7 M 3. 4 . 5 10- 6 M 4. 6 . 4 10- 4 M 5. 7 . 4 10- 5 M Explanation: [NH 3 ] = 0.20 M [NH + 4 ] = 0.30 M K b = 1 . 8 10- 5 NH 3 + H 2 O NH + 4 + OH- K b = [NH 4 ][OH- ] [NH 3 ] = 1 . 8 10- 5 [OH- ] = K b [NH 3 ] [NH + 4 ] = (1 . 8 10- 5 )(0 . 2) . 3 = 1 . 2 10- 5 M 005 1.0 points What is the approximate pH of a solution in which the concentration of benzoic acid is 1.0 M and the concentration of sodium benzoate is 0.10 M? 1. 3.20 correct 2. 1.65 3. 5.20 ycs73 Homework 7 Fakhreddine (53605) 2 4. 6.64 5. 2.64 Explanation: bracketleftbig C 6 H 5 COO- bracketrightbig = 1 . 0 M [C 6 H 5 COOH] = 0 . 1 M pH = p K a + log parenleftBigg bracketleftbig C 6 H 5 COO- bracketrightbig [C 6 H 5 COOH] parenrightBigg =- log ( 6 . 3 10- 5 ) + log . 10 1 . = 3 . 20066 006 1.0 points What is the approximate pH of a solution in which the concentration of benzoic acid is 0.10 M and the concentration of sodium benzoate is 1.0 M? 1. 2.64 2. 3.20 3. 5.20 correct 4. 6.64 5. 1.65 Explanation: bracketleftbig C 6 H 5 COO- bracketrightbig = 1 . 0 M [C 6 H 5 COOH] = 0 . 1 M pH = p K a + log parenleftBigg bracketleftbig C 6 H 5 COO- bracketrightbig [C 6 H 5 COOH] parenrightBigg =- log ( 6 . 3 10- 5 ) + log parenleftbigg 1 . . 10 parenrightbigg = 5 . 20066 007 1.0 points The following solutions are mixed in equal volumes. I) 0.1 M HCl and 0.1 M NaCl II) 0.1 M HOCl and 0.1 M NaCl III) 0.1 M HOCl and 0.1 M NaOCl IV) 0.1 M HCl and 0.1 M NaOCl Which will give (a) buffer solution(s)?...
View Full Document

This note was uploaded on 04/15/2009 for the course CH 53625 taught by Professor Fakhreddine during the Spring '09 term at University of Texas at Austin.

Page1 / 7

Homework 07 - ycs73 Homework 7 Fakhreddine (53605) 1 This...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online