Question

Ammonia is present in wastewater largely due to human urine. Unionized ammonia (NH3) is the conjugate base of the ammonium ion (NH4+) with acid dissociation constant (KA) for NH4+ equal to 5.7 × 10^−10. Write the acid-base reaction for the deprotonation of the ammonium ion. Assume that a wastewater treatment plant does BOD oxidation only (i.e., no ammonia removal). What is the dominant ammonia species in the wastewater at pH 7: unionized ammonia or ammonium ion? Show calculations to validate answer.

Answer 1

Amm onia CNH Basic cubsbemce (omjugote acid of Ammania is Ammoiumlen NH Ht NH ox, if we need to wnite depHotonatin 0ammnium ion Then NHy (ag) AHHlag) CAeid (Bare) CAnsusen) Ala, to caleulate dominant ammoniaspecies at p we need to calulate pKa gisen 9-24 lappns) Ka= 5.7 x 0 p Kaz-lug57x10 Aln, the gAien pH=ph Thenefone, thi dominant species wlL he Bud if wnld e gtatthapk ithe Gen pt specu w be uniomized amua CAHT the domineat

Therefore, the answer to this question is ammonium ion.

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