Chem2 Practice Exam 2010sp

Chem2 Practice Exam 2010sp - Cover Type B TO BE RETURNED AT...

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Cover Type B TO BE RETURNED AT THE END OF THE EXAMINATION. THIS PAPER MUST NOT BE REMOVED FROM THE EXAM CENTRE SURNAME: ________________________ FIRST NAME: ________________________ STUDENT NUMBER: _____________________ COURSE: ________________________ SAMPLE EXAMINATION SUBJECT NAME : Chemistry 2 SUBJECT NO. : 65212 DAY/DATE : TIME ALLOWED : 3 hours 10 minutes START/END TIME : START , END This paper is designed to be completed in 3 hours. An extra 10 minutes has been added to the time allowed and it is recommended that you use this 10 minutes to read the paper before commencing to answer the questions. All questions should be attempted Please answer all questions in the spaces provided Electronic calculators may be used NOTE: only non-programmable calculators are permitted in the chemistry 2 examination
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Fundamental Constants Gas constant: R = 8.314 kPa L mol -1 K -1 or R = 8.314 J mol -1 K -1 Faraday’s constant F = 96485 C mol -1 or F = 96485 J V -1 mol -1 data and formulae atomic masses: H 1.008, C 12.011, N 14.01, O 16.00, Na 22.99, Cl 35.45, Al 26.98, Cr 52.00 K w = 1 × 10 - 14 at 25 ° C pH = pK a + log 10 [acid] [base] pOH = pK b + log 10 [base] [acid] t ½ = k ln2 = k 0.693 t ½ = 0 ] [ 1 A k [A] t = [A] 0 e - k t ln[A] t - ln[A] 0 = - kt 0 ] [ 1 ] [ 1 A A t - = kt E = E ° nF RT lnQ or E = E ° nF RT log e Q
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1 ..../over Question 1 (13 marks) - this section ~15 marks in the spring 2010 final exam (a) Which of the following would produce a buffered solution when equal volumes of the two solutions are mixed? Circle any correct answers 1. 0.01 M CH 3 COOH and 0.01 M NaOH 2. 0.01 M CH 3 COOH and 0.01 M HCl 3. 0.02 M CH 3 COOH and 0.01 M CH 3 CO 2 Na 4. 0.02 M CH 3 COOH and 0.01 M NaOH (b) In some natural systems the pH must be maintained within very narrow limits. For example in human blood the pH must remain close to 7.4 or cell deterioration occurs. Blood contains several buffers which control the pH. One such buffer is H 2 PO 4 - / HPO 4 2 - . A buffer solution is prepared by mixing 600 mL of a 0.060 M H 2 PO 4 - solution and 400 mL of a 0.150 M HPO 4 2 - solution. K a for H 2 PO 4 - is 6.4 × 10 - 8 i) What is the pH of the buffer solution?
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2 ..../over Question 1 (continued) ii) If 0.002 mole of HCl is now added to the buffer solution, assuming constant volume, calculate the new concentrations of H 2 PO 4 - and HPO 4 2 - and hence calculate the new pH of the solution. c) Calculate the pH of a solution which contains 0.002 mole HCl in 1 litre of deionised water.
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3 ..../over Question 1 (continued) (d) The following diagram represents the titration curve for the reaction between an aqueous solution of hydrochloric acid and an aqueous solution of ethylamine (a base, CH 3 CH 2 NH 2 ). i)
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Chem2 Practice Exam 2010sp - Cover Type B TO BE RETURNED AT...

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