hw7solution_pdf - So (dds785) Homework 7 Sutcliffe (52440)...

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: So (dds785) Homework 7 Sutcliffe (52440) 1 This print-out should have 18 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Some solid KClO 2 is added to a water solution of HClO 2 . Which of the following statements is correct? 1. pH of the solution increases. correct 2. [H 3 O + ] will remain the same. 3. [OH- ] of the solution decreases. 4. pH of the solution decreases. Explanation: 002 10.0 points Which response identifies the statements true of buffer solutions? l) A buffer solution could consist of equal concentrations of ammonia and ammo- nium bromide. 2) A buffer solution could consist of equal concentrations of perchloric acid (HClO 4 ) and sodium perchlorate. 3) A buffer solution will change only slightly in pH upon addition of small amounts of acid or base. 4) In a buffer solution containing benzoic acid (C 6 H 5 COOH) and sodium benzoate (NaC 6 H 5 COO) the species that reacts with added hydroxide ion is the benzoate ion. 1. 2, 3, 4 2. Another combination 3. 1, 4 4. 2, 3 5. 1, 3 correct Explanation: HA + H 2 O A- + H 3 O + B + H 2 O BH + + OH- NH + 4 is the conjugate acid of the weak base NH 3 ; C 6 H 5 COO- is the conjugate base of the weak acid C 6 H 5 COOH. HClO 4 is a strong acid. OH- ions introduced into an acid buffer system removes the H 3 O + . Buffers are composed of comparative amounts of a weak acid/base and its conjugate and allows only a small change in pH when an acid or base is added. 003 10.0 points Which of the following mixtures can produce a buffer? I) NH 3 + NaOH II) NH 3 + NH 4 Cl III) H + + OH- IV) HClO 2 + NaClO 2 V) (CH 3 ) 3 NHCl + (CH 3 ) 3 N 1. II, IV, and V only correct 2. II, III, and IV only 3. II only 4. IV only 5. I, III, and V only Explanation: A buffer contains a weak acid or weak base, plus the salt of that weak acid or base; or, a mixture which will have this composition after any acid-base reactions occur. 004 10.0 points What is the pH of a solution in which the concentration of hypochlorous acid is 0.50 M and the concentration of sodium hypochlorite is 1.0 M? ( K a for HOCl = 3 . 2 10- 8 .) 1. 8.10 2. 8.31 3. 7.19 So (dds785) Homework 7 Sutcliffe (52440) 2 4. 5.44 5. 7.49 6. 7.80 correct 7. 6.89 Explanation: [OCl- ] = 1.0 M [HOCl] = 0.50 M K a = 3 . 2 10- 8 pH = p K a + log parenleftbigg [OCl- ] [HOCl] parenrightbigg =- log(3 . 2 10- 8 ) + log parenleftbigg 1 . . 5 parenrightbigg = 7 . 79588 005 10.0 points A buffer (pH 3.70) was prepared by mixing 1.00 mole of formic acid and 1.00 mole of sodium formate to form an aqueous solution with a total volume of 1.00 L. To 400 mL of this solution was added 50.0 mL of 1.00 M NaOH. What is the pH of this solution?...
View Full Document

Page1 / 7

hw7solution_pdf - So (dds785) Homework 7 Sutcliffe (52440)...

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