# hw 4 - mj6727 hw04 McCord(53580 This print-out should have...

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mj6727 – hw04 – McCord – (53580) 1 This print-out should have 25 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points What is the hydroxide concentration [OH ] in an aqueous solution in which the hydronium ion concentration [H 3 O + ] is 1 × 10 5 M? 1. 1 × 10 9 M correct 2. 1 × 10 7 M 3. 1 × 10 5 M 4. 1 × 10 14 M Explanation: [H 3 O + ] = 1 × 10 5 M K w = [H 3 O + ][OH ] = 1 . 0 × 10 14 [OH ] = K w [H 3 O + ] = 1 . 0 × 10 14 1 × 10 5 = 1 × 10 9 M 002 10.0 points Which oF the Following is true in pure water at any temperature? 1. pH = 7.0 2. K w decreases with increasing tempera- ture. 3. [H 3 O + ][OH ] = 1.0 × 10 14 4. pH = 7.0 or greater than 7.0 5. [H 3 O + ] = [OH ] correct Explanation: K w is shown to INCREASE with increas- ing temperature. pH = 7 is only true when water is at 24 C. [H 3 O + ][OH ] = K w , which increases with temperature. At high temperatures pH can be less than 7. Thus [H 3 O + ] = [OH ] is the only case that is true. 003 10.0 points What is [H 3 O + ] when [OH ] = 3 . 3 × 10 9 M? 1. 1 . 0 × 10 7 M 2. 3 . 3 × 10 9 M 3. 3 . 3 × 10 5 M 4. 3 . 0 × 10 6 M correct 5. 6 . 6 × 10 5 M Explanation: [OH ] = 3 . 3 × 10 9 M K w = [H 3 O + ][OH ] = 1 × 10 14 [H 3 O + ] = K w [OH ] = 1 . 0 × 10 14 3 . 3 × 10 9 = 3 . 0 × 10 6 M 004 10.0 points What is [OH ] when [H 3 O + ] = 8 . 2 × 10 5 M? 1. 1 . 0 × 10 7 M 2. 6 . 3 × 10 9 M 3. 1 . 2 × 10 10 M correct 4. 8 . 2 × 10 5 M 5. 1 . 2 × 10 4 M Explanation: [H 3 O + ] = 8 . 2 × 10 5 M K w = [OH ][H 3 O + ] = 1 . 0 × 10 14 [OH ] = K w [H 3 O + ] = 1 . 0 × 10 14 8 . 2 × 10 5 = 1 . 2 × 10 10 M 005 10.0 points What is [OH ] in a 0.0050 M HCl solution? 1. 2 . 0 × 10 12 M correct

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mj6727 – hw04 – McCord – (53580) 2 2. 1 . 0 × 10 7 M 3. 5 . 0 × 10 3 M 4. 1 . 0 M 5. 6 . 6 × 10 5 M Explanation: [OH ] = 0 . 0050 M Since HCl is a strong acid, it completely dissociates and H + is 0 . 0050 M. HCl H + + Cl K w = [H + ][OH ] = 1 × 10 14 [OH ] = K w [H + ] = 1 × 10 14 0 . 0050 = 2 × 10 12 M 006 10.0 points What is the conjugate acid of NO 3 ? 1. NH 3 2. OH 3. HNO 3 correct 4. NO 2 5. H + 6. NO 3 2 Explanation: Since the question asks for the conjugate acid, we can assume NO 3 is acting as a base. This means that it is a proton acceptor. To
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hw 4 - mj6727 hw04 McCord(53580 This print-out should have...

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