Ephedrine, a central nervous system stimulant, is used in nasalsprays as a decongestant. this compound is a weak organic base: {/rm{c}}_{10} {/rm{h}}_{15} {/rm{on (}}aq{/rm{) }} + {/rm{h}}_2 {/rm{o}} (l{/rm{) }} / overrightarrow{/leftarrow} {/rm{c}}_{10} {/rm{h}}_{15} {/rm{onh}}^ + (aq) + {/rm{oh}}^ - (aq) a 0.035 {/rm m} solution of ephedrine has a{/rm ph} of 11.33. what is the equilibrium concentration of{/rm{c}}_{10} {/rm{h}}_{15} {/rm{on}}, {/rm{c}}_{10} {/rm{h}}_{15} {/rm{onh}}^ +, and oh-.

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Chemistry

Lindsay Guerra

23 October, 07:45

Ephedrine, a central nervous system stimulant, is used in nasalsprays as a decongestant. this compound is a weak organic base: {/rm{c}}_{10} {/rm{h}}_{15} {/rm{on (}}aq{/rm{) }} + {/rm{h}}_2 {/rm{o}} (l{/rm{) }} / overrightarrow{/leftarrow} {/rm{c}}_{10} {/rm{h}}_{15} {/rm{onh}}^ + (aq) + {/rm{oh}}^ - (aq) a 0.035 {/rm m} solution of ephedrine has a{/rm ph} of 11.33. what is the equilibrium concentration of{/rm{c}}_{10} {/rm{h}}_{15} {/rm{on}}, {/rm{c}}_{10} {/rm{h}}_{15} {/rm{onh}}^ +, and oh-.

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Xander · Answer 1

Ephedrine, a central nervous system stimulant, is used in nasal sprays as a decongestant. This compound is a weak organic base:

C10H15ON (aq) + H2O (l) - > C10H15ONH + (aq) + OH - (aq)

A 0.035 M solution of ephedrine has a pH of 11.33.

a) What are the equilibrium concentrations of C10H15ON, C10H15ONH +, and OH - ?

b) Calculate Kb for ephedrine.

c (C₁₀H₁₅NO) = 0,035 M.

pH = 11,33.

pOH = 14 - 11,33 = 2,67.

[OH ⁻] = 10∧ (-2,67) = 0,00213 M.

[OH ⁻] = [C₁₀H₁₅NOH⁺] = 0,00213 M.

[ C₁₀H₁₅NO] = 0,035 M - 0,00213 M = 0,03287 M.

Kb = [OH ⁻] · [C₁₀H₁₅NOH⁺] / [C₁₀H₁₅NO].

Kb = (0,00213 M) ² / 0,03287 M = 1,38·10⁻⁴.