Please take a seat in Row Seat according to the following map

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1 ABCDEG Name Practice Chem 105X Fall 2009 Keller Hour Exam 2 Chap 3 &4 Kotz Please take a seat in Row_ Seat_ according to the following map Please: Keep this booklet closed until instructed to open it. Turn off and remove from your person all electronic items including PDAs, cell phones, earbuds, pagers, computers, progammable and graphing calculators, and other similar devices. Place them in your purse or pack on the floor or at the back of the room. Place all papers, periodic tables, books, coats, packs, on the floor or at the front or back of the room. All you need are #2 pencils & a non-programmable calculator. Exam Directions This is a closed book, 60-minute exam. Use nothing but the materials supplied to answer the questions. There are a total of 9 pages in this exam, including the cover and back sheets. The attached back sheet contains reference information including constants and periodic table. For questions 19 and 20, show your work, use the correct number of significant figures, and include proper units in answer and in the work. Write legibly: if your answer cannot be read by the grader, no credit can be given. Write YOUR NAME and fill in your STUDENT # on ANSWER SHEET -- NOW. After you begin, write your NAME at the top of BOTH PAGE 6 and PAGE 7. Incorrect or missing NAMES or STUDENT NUMBER may result in DELAYED GRADING.

2 Part I. Multiple Choice 4 POINTS EACH Identify the letter of the choice that best completes the statement or answers the question. PUT YOUR ANSWER ON THE ANSWER SHEET PROVIDED. Marks in this section of the exam booklet will not be graded. 1. The reaction of elemental chlorine with potassium iodide yields elemental iodine and potassium chloride. Write a balanced chemical equation for this reaction. a. Cl 2 (g) + KI(s) I(s) + KCl 2 (s) b. Cl 2 (g) + 2 KI(s) I 2 (s) + 2 KCl(s) c. Cl 2 (g) + KI 2 (s) I 2 (s) + KCl 2 (s) d. Cl(g) + KI(s) I(s) + KCl(s) e. Cl 2 (g) + 2 K 2 I(s) I 2 (s) + 2 K 2 Cl(s) 2. The products of the complete combustion of octane, C 8 H 18, are carbon dioxide and water. Write a balanced chemical equation for this reaction. a. C 8 H 18 ( ) 8 C(s) + 9 H 2 (g) b. C 8 H 18 ( ) + 25 O 2 (g) 8 CO 2 (g) + 9 H 2 O(g) c. 2 C 8 H 18 ( ) + 25 O 2 (g) 16 CO 2 (g) + 18 H 2 O(g) d. C 8 H 18 ( ) + 16 O 2 (g) 8 CO 2 (g) + 9 H 2 (g) e. 2 C 8 H 18 ( ) + 17 O 2 (g) 16 CO(g) + 18 H 2 O(g) 3. Which of the following statements is/are correct? 1. Most ionic compounds containing ammonium ion are insoluble in water. 2. Most ionic compounds containing nitrate ion are insoluble in water. 3. Most ionic compounds containing carbonate ion are insoluble in water. a. 1 only b. 2 only c. 3 only d. 1 and 2 e. 1, 2, and 3 4. All of the following compounds are insoluble in water except. a. BaSO 4 b. AgI c. CuS d. Ca(ClO 4 ) 2 e. PbCrO 4 5. If an aqueous solution of is added to a mixture of Ba 2+ and Fe 3+, the barium ion will precipitate, but the iron ion will remain in solution. a. NaOH b. Na 2 SO 4 c. K 3 PO 4 d. KCl e. Pb(NO 3 ) 2 2

3 6. What is the net ionic equation for the reaction of aqueous sodium hydroxide and aqueous iron(ii) chloride? a. Na + (aq) + OH (aq) NaOH(s) b. Na + (aq) + Cl (aq) NaCl(s) c. Fe 2+ (aq) + 2 OH (aq) Fe(OH) 2 (s) d. Fe 2+ (aq) + OH (aq) FeOH + (s) e. Fe 2+ (aq) + 2 Cl (aq) FeCl 2 (s) 7. What are the spectator ions in the reaction between aqueous hydrochloric acid and ammonia? a. H + only b. Cl only c. H + and NH 4 + d. Cl and NH 4 + e. H +, Cl, and NH Write a balanced net ionic equation for the reaction of barium carbonate and aqueous hydrochloric acid. a. BaCO 3 (s) + 2 H + (aq) Ba 2+ (aq) + CO 3 2 (aq) + H 2 (g) b. BaCO 3 (s) + 2 H + (aq) Ba 2+ (aq) + CO 2 (g) + H 2 O( ) c. BaCO 3 (s) + 2 HCl(aq) BaCl 2 (aq) + H 2 CO 3 (aq) d. BaCO 3 (s) + 2 H + (aq) Ba 2+ (aq) + H 2 CO 3 (s) e. BaCO 3 (s) + 2 H + (aq) BaO(s) + CO 2 (g) + H 2 (g) 9. Which species is oxidized in the reaction below? I (aq) + ClO (aq) IO (aq) + Cl (aq) a. I b. H 2 O c. Cl d. IO e. ClO 10. Which of the following chemical equations show oxidation-reduction reactions? 1. Mg(s) + I 2 (aq) MgI 2 (s) 2. Pb(ClO 4 ) 2 (aq) + 2 KI(aq) PbI 2 (s) + 2 NaClO 4 (aq) 3. Fe 2 O 3 (s) + 3 CO(g) 2 Fe(s) + 3 CO 2 (g) a. 1 only b. 2 only c. 1 and 2 d. 1 and 3 e. 2 and 3 3

4 11. Magnesium reacts with chlorine gas to produce magnesium chloride. How many moles of Mg will react with 2.6 moles of Cl 2? a. 1.3 mol b. 2.6 mol c. 3.9 mol d. 5.2 mol e. 7.8 mol 12. The compound P 4 S 3 is used in matches. It reacts with oxygen to produce P 4 O 10 and SO 2. The unbalanced chemical equation is shown below. P 4 S 3 (s) + O 2 (g) P 4 O 10 (s) + SO 2 (g) What mass of SO 2 is produced from the combustion of g P 4 S 3? (SEE ALSO Question 19) a g b g c g d g e g 13. How many moles of Cu 2 O(s) can be produced from the reaction of 0.66 mol Cu(s) with 0.40 mol O 2 (g)? a mol b mol c mol d mol e mol 14. Sulfur hexafluoride is produced by reacting elemental sulfur with fluorine gas. S 8 (s) + 24 F 2 (g) 8 SF 6 (g) What is the percent yield if 18.3 g SF 6 is isolated from the reaction of 10.0 g S 8 and 30.0 g F 2? a. 40.2% b. 45.8% c. 47.6% d. 54.6% e. 61.0% 4

5 15. A g sample of a hydrocarbon is combusted to give g of H 2 O and g of CO 2. What is the empirical formula of the compound? a. CH b. CH 2 c. C 2 H 3 d. C 3 H 4 e. C 5 H If 8.19 g KIO 3 is dissolved in enough water to make ml of solution, what is the molarity of the potassium iodate solution? The molar mass of KIO 3 is g/mol. a M b M c M d M e M 17. The ph of a vinegar solution is What is the H 3 O + concentration of the solution? a M b M c M d. 1.4 M e M 18. If g of impure soda ash (Na 2 CO 3 ) is titrated with ml of M HCl, what is the percent purity of the soda ash? Na 2 CO 3 (aq) + 2 HCl(aq) 2 NaCl(aq) + H 2 O( ) + CO 2 (g) a % b % c % d % e % (SEE ALSO Question 20) 5

6 ABCDEG PRINT CLEARLY Name Part II. 10 points per question For full credit, you must show your work including units in all conversion factors and the final answer; use the correct number of significant figures; and round off correctly. WRITE CLEARLY: if the grader cannot read your writing, no credit will be assigned. Question 19 Show the complete solution to Question 12: The compound P 4 S 3 is used in matches. It reacts with oxygen to produce P 4 O 10 and SO 2. The unbalanced chemical equation is shown below. P 4 S 3 (s) + O 2 (g) P 4 O 10 (s) + SO 2 (g) What mass of SO 2 is produced from the combustion of g P 4 S 3? 6

7 ABCDEG PRINT CLEARLY Name For full credit, you must include units in all conversion factors and the final answer; use the correct number of significant figures; and round off correctly. WRITE CLEARLY: if the grader cannot read your writing, no credit will be assigned. Question 20 Show the complete solution for Question 18. If g of impure soda ash (Na 2 CO 3 ) is titrated with ml of M HCl, what is the percent purity of the soda ash? Na 2 CO 3 (aq) + 2 HCl(aq) 2 NaCl(aq) + H 2 O( ) + CO 2 (g) 7

8 Avogadro s number = x in = cm 1 amu = x g 1 mile = ft 8

9 Scratch paper you may tear off. 9