Ch 14 QUIZ - AP Chemistry

Ch 14 QUIZ - AP Chemistry

Name:_______________________________ Date:_________________ Hr:____AP CHEMISTRYCh 14 – Acids and BasesACIDS AND BASES QUIZTOTAL: /50You may use your chemistry textbook, class notes, handouts, labs, or any other notes youmake. You may only collaborate with students currently enrolled in AP Chemistry at GHS. Youmay not use any adults, the internet, or other electronic resources for this quiz. You maychoose not to collaborate with another student (please respect the decision of those whochoose to work on their own). Show all work with appropriate significant figures for full credit.Multiple Choice (10 points – 2 points each)Identify the letter of the choice that best completes the statement or answers the question.Mathematical set-ups and/or verbal reasoning must be given for each question, which mightinclude why other choices may not be correct. Attach a sheet of paper if needed. No creditwill be awarded for only recording the letter of the answer.QUIZ_____ 1. Equal masses of each of the following substances are dissolved in separate samplesof water to give 500.0 mL of each solution. Which substance would produce thesolution with the lowest pH?a. NH 3b. HNO 3c. HCld. HClO 3_____ 2. For the reaction: H 2 O(l) H + (aq) + OH - (aq), K w = 1 x 10 -14 at 25°C. 55.9 kJ of heat isevolved when one mole of H + (aq) reacts with one mole of OH - (aq). At 80°C, the K w and pHfor pure water is…a. K w > 1 x 10 -14 and pH < 7b. K w > 1 x 10 -14 and pH > 7c. K w < 1 x 10 -14 and pH < 7d. K w < 1 x 10 -14 and pH > 72014Page 1 of 6

Name:_______________________________ Date:_________________ Hr:____AP CHEMISTRYCh 14 – Acids and Bases_____ 3. NaOCl is completely dissociated in water to form Na + (aq) and OCl - (aq). In solution,OCl - hydrolyzes according to the equation OCl - (aq) + H 2 O(l) HOCl(aq) + OH - (aq). 100. mLof pure water at constant temperature is added to a 100.-mL solution of 0.10 M NaOCl.When the solution reaches equilibrium again, the…a. [H + ] has decreased.b. pH of the solution has decreased.c. [HOCl] has increased.d. value of the equilibrium constant has halved.QUIZ_____ 4. The pH of several common substances are given below.From the above pH values, we can deduce that the concentration of hydrogen ions is abouta. twice as great in household bleach than in milk.b. 1,000,000 times greater in soap than in wine.c. four times greater in cola than in household bleach.d. 1,000 times greater in distilled water than in soap._____ 5. Methanoic acid (K a = 1.82 x 10 -4 ) and ethanoic acid (K a = 1.74 x 10 -5 ) are both weakacids. Two separate solutions were prepared, one of 0.1 M methanoic acid and the other of0.1 M ethanoic acid. Which one of the following would be present in the highestconcentration?a. CH 3 COOH in the ethanoic acid solutionb. CH 3 COO - in the ethanoic acid solutionc. HCOOH in the methanoic acid solutiond. HCOO - in the methanoic acid solution2014Page 2 of 6

Name:_______________________________ Date:_________________ Hr:____AP CHEMISTRYCh 14 – Acids and BasesConstructed-Response (40 points)Your responses to these questions will be scored on the basis of the accuracy and relevance ofthe information cited. Explanations should be clear and well organized. Specific answers arepreferable to broad, diffuse responses.-6. (3 points) MnO 4 Mn 2+2-2-SO 3 SO 4a. Write and balance the chemical equation (showing all your work, of course) for theoxidation-reduction reaction in acidic solution for the half-reactions shown above.QUIZb. What are the initial and final oxidation states for the substance(s) being oxidized?Justify your response.7. (3 points) When sulfur trioxide gas is bubbled through excess water, a sulfuric acid solutionis formed. Write the balanced net ionic equation for this reaction and determine what volumeof sulfur trioxide gas would be needed at 28 °C and 750 torr to completely react with 1.4 molesof water.2014Page 3 of 6

Name:_______________________________ Date:_________________ Hr:____AP CHEMISTRYCh 14 – Acids and BasesQUIZ8. (6 points) A solution is prepared by adding 50.0 mL of 0.0555 M HCl and 30.0 mL of 0.111 MHNO 3 . Calculate the concentrations of all ionic species in this solution. What is the pH of theresulting solution? Note: Don’t forget to calculate the concentrations of all ionic species!9. (6 points) Monochloroacetic acid is a skin irritant that is used in “chemical peels” intended toremove the top layer of dead skin of the face and ultimately improve the complexion. Thevalue of K a for monochloroacetic acid is 1.35 x 10 -3 . Calculate the pH of a 0.10 M solution ofmonochloroacetic acid. Predict whether monochloroacetic acid is stronger or weaker acid thanacetic acid. Justify your response using concepts related to atomic structure, bonding, and/orinterparticle forces (in other words, do not justify your response using quantitative conceptsrelated to equilibrium calculations).2014Page 4 of 6

Name:_______________________________ Date:_________________ Hr:____AP CHEMISTRYCh 14 – Acids and BasesQUIZ10. (5 points) Calculate the pH of a 5.0 x 10 -3 M solution of H 2 SO 4 .11. (4 points) Zinc hydroxide is an amphoteric substance. Write equations (& structures) thatshow Zn(OH) 2 as a Brønsted-Lowry base toward H + and as a Lewis acid toward OH - . Use arrowsto show to movement of protons and/or electrons. Put only your final answer in the box.Brønsted-Lowry base toward H + :Lewis acid toward OH - :12. (5 points) An unknown sodium salt, NaX, is to be identified. When 0.100 moles of the salt isdissolved in 1.00 L of water, the pH of the solution is 8.07. What is the identity of the anion, X?Defend your answer. Hint: Be sure to use Table A5.1 “Values of K a for Some CommonMonoprotic Acids” to assist you.2014Page 5 of 6

Name:_______________________________ Date:_________________ Hr:____AP CHEMISTRYCh 14 – Acids and BasesQUIZ13. (3 points) Benzoic acid, C 6 H 5 COOH, has a K a of 6.4 x 10 -5 . At 25°C, a saturated solution ofbenzoic acid has a pH of 2.80. Calculate the mass of solid benzoic acid required to form asaturated solution with a volume of 1.0 L.14. (5 points) Rank the following 0.10 M solutions in order of increasing pH. Defend yourranking. C 6 H 5 NH 2 , NaNO 3 , NaOH, HNO 3 , C 6 H 5 OH, KC 6 H 5 O, C 6 H 5 NH 3 NO 3I affirm that the work shown on this quiz is entirely my own effort and that no resources other than those specifiedwere used.____________________________________Student Signature2014Page 6 of 6

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