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Unformatted text preview: Version 239/ADCDD – Quiz 4 – Lyon – (52635) 1 This print-out should have 8 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 1 2 3 4 5 6 7 AA AB AC AD BA BB BC 8 9 10 BACK NEXT BD CA CB CC CD Retries are allowed on this quiz. The num- ber of retries are determined by the number of possible responses to the question. Negative points are given for all incorrect answers. Pos- itive points are given only for correct answers. Remember that questions with only two pos- sible answers are worth +10, if answered cor- rectly and -10, if answered incorrectly. If you do not know the answer to a question with only two possible responses, skip it, a zero does not hurt your score as much as minus 10. 001 10.0 points A water solution is considered basic when which of the following is true? Note: the brackets represent the concentration of the ions in mol/L. 1. [H + ] > [OH- ] 2. [OH- ] < [H + ] 3. [H + ] = [OH- ] 4. [OH- ] > [H + ] correct Explanation: An acid is defined by its ability to produce H + ions in aqueous solution. A base is defined by its ability to produce OH- ions in aque- ous solution. When both H + ions and OH- ions are present in water, the solution is con- sidered acidic, basic or neutral depending on the concentration of the specific ions. When [ H + ] > [ OH- ], the solution is acidic. When [ OH- ] > [ H + ], the solution is basic. When [ H + ] = [ OH- ], the solution is neutral. 002 10.0 points During an acid/base titration the point at which the indicator phenolphthalein changes color (suggesting the titration be stopped) is called the point. 1. standardization 2. end correct 3. indicator 4. equivalence 5. primary standard Explanation: The point in strong acid/strong base titra- tions in which [H + ] = [OH- ] is called the equivalence point. The solution is neutral since there are no excess H...
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This note was uploaded on 03/15/2010 for the course CH 52645 taught by Professor Lyon during the Spring '10 term at University of Texas at Austin.
- Spring '10