HELP PLEASE! Model 3: Some Potential Acids and Some Potential Bases Are So Weak
ID: 883091 • Letter: H
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HELP PLEASE!
Model 3: Some Potential Acids and Some Potential Bases Are So Weak That They Do Not Affect the pH of the Solution. Any acid with a K. less than 10,aa be treated as acid with a K,less than 10 can be treated ir x,- ln water). ny base wicha &, less than 10 can be treated as rK-(i water) The catiens of alkali metals and alkaline earth metals act as neither acids nor bases in solution 0.I MKc 0.I M KNO .1MNH pH 70 pH 8.2 pH-5.1 K" no effect on p C no effect on p K" no effect on pH NO, makes solution basicno effect on pH NI4. makes solution acidic Table 1. The values of K, for conjugate bases of some strong acids Hase Critical Thinking Questions 8. Fill in the missing entries in Table 1. 9· The chloride ion is the conjugate base of hydrochloric acid. Explain why Ct-does in not produce a basic solution when dissolved in water 1.00 molar solution of NaBr. Ex Explain 0. To 2 significant figures, predict the ph of a 1.00 molar solution of NaBr. your reasoning carefully Explain why the conjugate bases of the strong acids do not produce basic solutions when dissolved in waterExplanation / Answer
Kb = Kw/Ka = 1x10^-14/Ka
8. So feeding the given values in table we get,
Table 1:
Acid Ka Conjugate base Kb
HBr 1x10^9 Br- 1x10^-23 (or 0)
HCl 1x10^6 Cl- 1x10^-20 (or 0)
HNO3 28 NO3- 3.57x10^-16 (or 0)
Since the values of Kb are less then 10^-15 we can take it as zero as disscussed above.
9. In order to act give a basic solution the anion must hydrolyze in water that is it must accept a proton from H2O to form OH-. This is not the case with conjugate base of strong acid such as Cl- and thus it does not give basic solution in water.
10. pH of NaBr solution would be neutral that is it would have a pH of 7. Br- is a conjugate base of a strong acid and would not hydrolyze in water.
Once again, the conjugate bases of strong acids do not hydrolyze in water and thus no OH- is produced. Thus the solutions are not basic.
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