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Published byJerome Jeffrey Briggs Modified over 6 years ago
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Monday, November 16th Find your popsicle stick
Get out your notes Make sure everyone at your table has a whiteboard, dry erase marker, and rag
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1 What are two kinds of molecules that commonly function as weak bases?
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2 Write the chemical equation and Kb expression for the ionization of the following bases: Dimethylamine: (CH3)2NH Carbonate ion: CO32- Formate ion: CHO2-
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3 Calculate the molar concentration of hydroxide ions in a 0.075M solution of ethylamine (C3H5NH2) Kb = 6.4 x 10-4 What’s the pH?
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4 Ephedrine, a central nervous system stimulant, is used in nasal spray as a decongestant. This compound is a weak organic base: C10H15ON(aq) + H2O(l) ↔ C10H15ONH+(aq) + OH-(aq) A 0.035M solution has a pH of What are the concentrations of all the species? Calculate Kb for ephedrine.
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5 Although the acid-dissociation constant for phenol (C6H5OH) is listed in your book, the dissociation constant for the phenolate ion (C6H5O-) is not. Explain why it is not necessary to list both. The Ka for phenol is 1.3 x Calculate the Kb for the phenolate ion. Is the phenolate ion a weaker or stronger base than ammonia? (Kb for ammonia = 1.8 x 10-8) Which is more likely to occur – the acid-dissociation of phenol or base-dissociation of phenolate? Explain.
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6 Given that Ka for acetic acid is 1.8 x 10-8 and the Ka for hypochlorous acid is 3.0 x 10-8 Which is the stronger acid? Why? Which is the stronger base – the acetate ion or the hypochlorite ion? Why? Calculate the Kb values for the acetate ion and the hypochlorite ion.
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Note on effects of Ka lab
You SHOULD have used the same volume of NaOH in both trials If this didn’t happen, include potential reasons why in your error analysis
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To Do Work on review questions 18-25 (due Tuesday)
Effects of Ka lab report (due Wed.) Problem Set 4 (due Tuesday) Problem Set 5 (due Wednesday) Ch 16 test Thursday 17.1 notes due Friday Ch. Retakes must be done by Tuesday, 11/24
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