Exam3CKey

# Exam3CKey - 1(25 What is the pH(to nearest 0.01 pH unit of...

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1) (25) What is the pH (to nearest 0.01 pH unit) of a solution prepared by mixing 59.0 mL of 0.526 M HCl and 79.0 mL of 0.303 M NaOH? start with : 59.0 mL x 0.526 M = 31.0 mmol H 3 O 1+ 79.0 mL x 0.303 M = 23.9 mmol OH 1- H 3 O 1+ + OH 1- ¾ 2 H 2 O i 31.0 23.9 mmol -23.9 -23.9 mmol e 7.1 0 mmol strong acid pH = - log mL 138.0 mmol 7.1 = pH = 1.29 2) (20) Find the value of K for the equilibrium established when aqueous solutions of NaBrO and HCN are mixed. BrO 1- + HCN ¾ HBrO + CN 1- K = acid) (produced K acid) (reacting K a a K = 70 . 8 40 . 9 10 10 - - = - - 9 0 1 10 x 1.99 10 x 3.98 = K = 0.199 3) (20) What are the hydronium and hydroxide ion concentrations in a pH = 12.10 solution? pH = 12.10 pOH = 14.00 – 12.10 = 1.90 [H 3 O 1+ ] = 10 -12.10 [OH 1- ] = 10 -1.90 [H 3 O 1+ ] = 7.94 x 10 -13 M [OH 1- ] = 1.26 x 10 -2 M

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4) a) (25) How many grams of NH 3 (M m = 17.03 g/mol) must be added to 275 mL of a 0.612 M
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## This note was uploaded on 10/03/2008 for the course CH 201 taught by Professor Warren during the Spring '07 term at N.C. State.

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Exam3CKey - 1(25 What is the pH(to nearest 0.01 pH unit of...

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