Exam_3_2008_B_key - EAS 1600 - INTRODUCTION TO...

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Unformatted text preview: EAS 1600 - INTRODUCTION TO ENVIRONMENTAL SCIENCES Fall, 2008 Exam 3 - 11/24//08 < Answer all Questions < Show all your work < Place your name on each page < This is a closed-book exam, notes are not allowed; all are expected to comply with the Georgia Tech Honor Code. Please also note that cell phone use or contact with any other person is not allowed. I am aware and in compliance with the Georgia Tech Honor Code and I agree to abide by the grading policies of this class. Signature: ____________________________________________________________ Print Name: ___________________________________________________________ Lab Section: ___________________ B 1 1. An aqueous solutions has a pH of 11.5. What is the H + concentration in the solution? (5 pts) pH = -log[H + ] 11.5 = -log[H + ] [H + ] = 10-11.5 = 3 x 10-12 2. a. A solution contains carbonic acid (H 2 CO 3 ) and bicarbonate (HCO 3- ). The carbonic acid has a concentration of 0.1 mole/l and bicarbonate is 10 times larger. What is the pH of the solution? (10 pts) H 2 CO 3 H + HCO 3- 0.1 0 1 -x +x +x 0.1- x x 1 + x 7 3 2 3 10 3 . 4 ] ][ [ − − + = x CO H HCO H (this could be neglected-very small) 7 10 3 . 4 1 . ) 1 )( ( − = − + x x x x 8 10 3 . 4 − = x x 37 . 7 ) 10 3 . 4 log( 8 = ⇒ = − pH x pH b. Is the solution above buffered? Why? (5 pts) yes, it contains a weak acid and its conjugate base i.e. carbonic acid and bicarbonate 2 c. What would the pH of the solution above (in part a) be if you were to add 0.05 mole/l c....
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This note was uploaded on 02/08/2011 for the course EAS 1600 taught by Professor Jimstjohn during the Fall '08 term at Georgia Institute of Technology.

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Exam_3_2008_B_key - EAS 1600 - INTRODUCTION TO...

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