PS%203-2

PS%203-2 - S and 9.5x10-4 M H 2 S solution be more acidic,...

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1 AEST A601 Aquatic Process Chemistry Problem Set 3 Part 2 1. Determine solution pH in each of the following cases using a log C-pH diagram. Check your result by substituting the computed concentrations of all the species into the K a equation. a. 1x10 -3 M NaAc (sodium acetate) b. 1x10 -4 M NH 4 Cl c. 5x10 -3 M NaCN d. 5x10 -3 M HOCl e. 1x10 -3 M HAc 2. Problem 4-4 (Benjamin). Below is a log C-pH diagram for 10 -3 M hydrogen sulfide (H 2 S), a diprotic acid with pK a1 = 6.99 and pK a2 = 12.92. a. Label the lines with the species they represent and assign correct values to the axes. b. Draw lines for H + and OH - on the diagram. c. What is the pH of a solution of 10 -4 M NaHS and 9x10 -4 M H 2 S solution? d. Would a solution made by adding 0.5x10 -4 M Na 2
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Unformatted text preview: S and 9.5x10-4 M H 2 S solution be more acidic, more alkaline, or the same as the solution in part (c)? Explain your answer in one or two sentences or equations. 3. Problem 5-2 (Benjamin). How much does the alkalinity change upon addition of 10-4 M of the following chemicals? Assume alkalinity is determined by titration to pH 4.7 and the water is initially at pH 7.5 due to the presence of an unknown mixture of weak acids and bases. Briefly explain your reasoning. a. i. HCl ii. NaOH iii. Na 2 CO 3 iv. NaHCO 3 v. CO 2 vi. NaH 2 Cit vii. Na 2 SO 4 b. Would answers to parts (iii) and (iv) be different, and if so how, if the water was inititally at pH 9.0? If the water was initially at pH 4.7?...
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