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[Exam Tutorial] Chem 1AA3 Fall 2011 Term Test 1 Questions

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Department
Chemistry
Course
CHEM 1AA3
Professor
All Professors
Semester
Winter

Description
Student Name: _______________________ Student No: _________________________ Chemistry 1AA3 Test 1 January 28, 2011 McMaster University VERSION 1 Instructors: P. Berti, J. Landry, P. Lock, H. Stöver Durm10.n: This test contains 18 numbered pages printed on both sides. There are 25 multiple-choice questions appearing on pages numbered 3 to 16. Pages 17 and 18 are extra space for rough work. Page 19 includes some useful data and equations. There is a periodic table on page 20. You may tear off the last page to view the periodic table and to do your rough work. Winter 2012 – Omit questions 20 & You must enter your name and student number on the question sheets, as well as on the answer sheet. Your invigilator will be checking your student card for identification. Kinetics not covered on test 1. You are responsible for ensuring that your copy of the question paper is complete. Bring any discrepancy to the attention of your invigilator. Questions 1 to 20 are each worth 2 marks, questions 21 - 25 are each worth 3 marks; the total marks available are 55. There is no additional penalty for incorrect answers. BE SURE TO ENTER THE CORRECT VERSION OF YOUR TEST (shown near the top of page 1), IN THE SPACE PROVIDED ON THE ANSWER SHEET. ANSWER ALL QUESTIONS ON THE ANSWER SHEET, IN PENCIL. Instructions for entering multiple-choice answers are given on page 2. SELECT ONE AND ONLY ONE ANSWER FOR EACH QUESTION from the answers (A) through (E). No work written on the question sheets will be marked. The question sheets may be collected and reviewed in cases of suspected academic dishonesty. Academic dishonesty may include, among otheractions, communication of any kind (verbal, visual, etc.) between students, sharing of materials between students, copying or looking at other students’ work. If you have a problem, please ask the invigilator to deal with it for you. Do not make contact with other students directly. Keep your eyes on your own paper – looking around the room may be interpreted as an attempt to copy. Only Casio FX 991 MS electronic calculators may be used; but they must NOT be transferred between students. Use of periodic tables or any aids, other than those provided, is not allowed. 1 Continued on next page… Student Name: _______________________ Student No: _________________________ OMR EXAMINATION – STUDENT INSTRUCTIONS NOTE: IT IS YOUR RESPONSIBILITY TO ENSURE THAT THE ANSWER SHEET IS PROPERLY COMPLETED: YOUT EXAMINIATION RESULT DEPENDS UPON PROPER ATTENTION TO THESE INSTRUCTIONS. The scanner, which reads the sheets, sens es the bubble shaded areas by their non- reflection of light. A heavy mark must be m ade, completely filling the circular bubble, with an HB pencil. Marks m ade with a pen will NOT be sensed. Erasures must be thorough or the scanner will stil l sense a mark. Do NOT use correction fluid on the sheets. Do NOT put any unnecessary marks or writing on the sheet. 1. On SIDE 1 (red side) of t he form, in the top box, in pe n, print your student number, name, course name, and the date in the s paces provided. Then you MUST write your signature, in the space marked SIGNATURE. 2. In the second box, with a pencil, mark your student number, exam version number in the space provided and fill in the corresponding bubble numbers underneath. 3. Answers: mark only ONE choice from the alternatives (A,B,C,D,E) provided for each question. The question number is to the left of the bubbles. Make sure that the number of the question on t he scan sheet is the same as the number on the test paper. 4. Pay particular attention to the Marking+ Directions on the form. 5. Begin answering the question using the first set of bubbles, marked “1”. Version number 2 Continued on next page… Student Name: _______________________ Student No: _________________________ VERSION 1. Enter your version number in the correct column on your scan sheet (see p. 2 for details). Section #1 – These questions are worth two marks each. 1. The pH of a 0.1 M solution of a strong acid is: A) 12 B) 13 C) 2 D) 7 E) 1 3 2 3  2. The pH of a PO 4 /HPO 4 system is 12.12. What is the ratio of [PO 4 ]/[ HPO 4 ] in this solution? 2- 13 Data: K (aPO ) =44.2  10 A) 0.98 B) 1.9 C) 0.55 D) 2.4 E) 0.41 3 Continued on next page… Student Name: _______________________ Student No: _________________________ 3. Which of the following combinations of solutions can be used to prepare a buffer solution? (All solutions are 1.0 M) A) 25 mL HCl + 25 mL KNO 2 B) 25mLHNO 3+ 15 mL NaOH C) 15 mL NaOH + 25 mL HNO 2 D) 25 mL NaOH + 25 mL KNO 2 E) 15 mL HCl + 25 mL KNO 3 4. The effect on pH of adding 20.0 mL of 0.010 M NaOH(aq) to 1.00L of a solution that is 0.20 M NH (aq) and 0.20 M NH Cl(aq) is to: 3 4 A) lower the pH by several units B) have no effect on pH C) lower the pH slightly D) raise the pH slightly E) raise the pH by several units 5. Which of the following is/are the conjugate acid of a strong base? + + (i) NH 4 (ii) 2 O (iii) 3 O (iv) H2(v) CH C3OH A) iii,ii B) i, iii, v C) i, D) iii,v E) ii 4 Continued on next page… Student Name: _______________________ Student No: _________________________ 6. Which indicator is best suited to determine the equivalence point of a titration of diethylamine with HBr? Data: pK (biethylamine) = 3.16 A) Bromcresob llu(p K HIN≈ 4) B) Methyl Violet (pK ≈ 1) HIN C) Phenolpthalein(p K HIN ≈ 9) D) Phenol Red (pK HIN≈ 7.5) E) Alizarin Yellow-R (pK HIN≈ 11) 7. Which of the following statements about buffers is FALSE? A) Buffers resist changes in pH from the addition of limiting amounts of strong acid or strong base. B) The percent ionization of the weak acid in a buffer system is less than the percent ionization of the weak acid on its own because of the common ion effect. C) The buffer capacity for a weak acid (HA) / weak base (A ) system is at a maximum when [A ] and [HA] are in ratios of 1:10 or 10:1. D) Buffer range is the range of pH values over which a buffer solution resists changes to pH, and the most effective range is pH = pKa± 1. E) Adding a small amount of water to a buffer does not change the pH because the ratio of weak acid and weak base remains the same. 8. A student obtains an unknown indicator which is colourless in neutral water. When placed in a 0.1 M solution of HCl or NH Cl, the indicator remains colourless. When 4 placed in 0.1 M solution of NaNO ,2the indicator turns blue. What is the approximate pK af the indicator? A) 13.0 - 14.0 B) 1.0 - 2.0 C) 8.0 - 9.0 D) 2.0 - 4.0 E) 5.0 - 6.0 5 Continued on next page… Student Name: _______________________ Student No: _________________________ 9. In the titration of a weak acid with a strong base, the solution at the equivalence point is? A) neutral B) stronglbasic C) weaklyacidic D) stronglacidic E) weaklybasic 10. What is the pH of the solution that results when the following substances are added to water to create 1.00 L of solution?  10 Data: K bCH CO3  = 5.6  10 0.100 mol HCl 0.250 mol NaCH 3COO 0.100 mol NaCl A) 5.13 B) 1.00 C) 5.15 D) 4.92 E) 3.26 6 Continued on next page… Student Name: _______________________ Student No: _________________________ 11. Indicatethe pH of a 0.020 M solution of benzoic acid in water. Data: K (benzoic acid) = 6.3 × 10 -5 a A) 3.12 B) 2.95 C) 2.85 D) 4.50 E) 2.61 12. Acetic acid (10.00 mL) is added to a beaker and diluted with ≈40 mL of distilled water before starting the titration with NaOH. The addition of ≈40 mL of distilled water will change which of the following: A) The pH of the NaOH solution B) The volume of NaOH required to reach the maximum buffer capacity C) The initial pH of the acetic acid solution D) The volume of NaOH needed to reach the equivalence point E) The pH at the 1/2 equivalence point
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