[K']

Calculate the pH of a solution prepared by mixing 100.0 mL of 1.20 M ethanolamine, C2H5ONH2+ with 50.0 mL of 1.0 M HCl. Ka for C2H5ONH3+ is 3.6 x 10-10 M. 

no. moles C2H5ONH2 = 0.120 mol
no. moles HCl = 0.050 mol

after reaction:                         
no. moles C2H5ONH2 = 0.070 mol
no. molesC2H5ONH3+ = 0.050 mol


Here is the answer: pH = 9.59

My question is, how does this reaction take place?

 

[Borek]

Simple protonation of -NH₂, not much different from the ammonia reaction.