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Unformatted text preview: obennoskey (blo242) – Pre-lab 9 – Lyon – (52635) 1 This print-out should have 10 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points The pH of 0 . 015 M HNO 2 (nitrous acid) aque- ous solution was measured to be 2 . 63. What is the value of p K a of nitrous acid? 1. 2.63 2. 2.90 3. 3.36 4. 0.97 5. 3.59 6. 4.24 002 10.0 points Calculate the hydrogen ion concentration for an aqueous solution that has a pH of 3.45. 1. 2 . 8 × 10- 11 M 2. 0.54 M 3. 1.22 M 4. 3 . 5 × 10- 4 M 5. 3 . 2 × 10- 2 M 003 10.0 points If you have a solution of a strong monoprotic acid and a solution of a weak monoprotic acid of comparable concentrations, would you expect the pH of those two solutions to be the same or different? Explain your answer. 1. The strong acid will dissociate completely, releasing more H + ions into solution. The weak acid will only partly dissociate, releas- ing fewer H + ions into solution. Since pH decreases with increasing H + concentration, the solution of the strong acid will have a lower pH. 2. The strong acid will dissociate more than the weak acid. Since pH is a measure of acid strength, the acid that stays together best will have the higher acid concentration. The weak acid will therefore have more intact acid molecules in the solution and will have a lower pH. 3. The two solutions should have the same pH if they are in an aqueous solution be- cause a strong acid and a weak acid are both more acidic than water itself, and they should therefore dissociate equally.therefore dissociate equally....
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This note was uploaded on 04/14/2010 for the course CH CH302 taught by Professor Mccord during the Spring '10 term at University of Texas at Dallas, Richardson.
- Spring '10