Question

Critical Skills 9 Acid-Base Equilibria) Due: 6 pm Monday March 30 upload to Gradescope Class time: 9:30 11:00 2:00 (from back of page) 1. Consider the conjugate acid-base pair NHA and NH, a. Write the acid dissociation (ionization) reaction for NHA" in water. Hint: NH."(aq) + HOME? Label each conjugate acid-base pair. b. Write the expression for equilibrium constant for this reaction ( ?) c. Write the base dissociation (Ionization) reaction for NH, in water. Hint: Nyaq) + HOS Label each conjugate acid-base pair. ? d. Write the expression for equilibrium constant for this reaction (K ? e. Use the results of parts b and d to demonstrate that K x K = K acid-base pair. This relationship holds for any conjugate f. Use the relationship in e to calculate Ko for NH, from K for NHa* and K. at 25°C. Show your work. K = 5.6 x 1080 2. On the back of this page use the information above to calculate the equilibrium concentrations of NH3, NHsand OH and determine the pH of a 0.10 Maqueous solution of ammonia at 25°C. Use the quadratic equation only if approximation fails. SHOW ALL WORK. Be sure to include: ICE table All equations in symbols first Explicit statement of assumptions and demonstration of their validity Final check of SigFigs Units Equilibrium concentration values by calculating Ko from the equilibrium concentrations pH (is it a basic pH?)

Answer 1

Answel To Acid dissociation of NHW in water, a VH SH acid * Hạ 45° Nam Hg) Conjugate base 6) Equilibrium constant Ka Chat) = [nm]. (11304 who c) Base dissociation of NH3 in water M Nhy Cag) + H2O(l) = Nyt @g) + OH(aq) base Conjugate acid a kb (rH₂) = [why [ot] [witz] 2), H2OQy: Hot @9). + oH" @ 3 Kw = [H +] CH) * H202)+ H2O (1) = OH + H30*@g) - RBL = acid base Kia Cavite) x Kyand] = [13] (190) x (wy)(011] [^Hi ] [NHg) - 0304] [or] = 'Kw kaxkb = kw dsscanned with CamScanner

B ka Contato - 5.6x10" ke at 25°c = "X10" Ka xkb - Kew kb (13) Cuma S ixioll 5.6 xiolo = 0.178x104 = 1:784105 criven H concentation of NH3. = Oulom Kb Cuts] ='1.78x105 Equation : NH₃ + H2O 2 What toh aq) () @co (aq) ist we can peepare ICE table, Why Cat H2023 € e .NH, + H . olm X O.Im-se . - CSScanned with CamScanner

Kb = [Nyt] [or] = Poe] (30) co.im so ACP Oolme 1.78x105 = Ş Kha 1.78x10 o. lmesc Asseme ris 700 Small, 1.78*10 DOP O:100m oce = 1178x10m x = 1.33 x103 m = 0.0013 m = 0.0013m = Com] GBH + POH : 14. POH = -log (0.0013] poh = 2.89 pH =:14 - 2.89 TE CS$canned wirl tamsiai na bagie pH {ph >7= bagie) anner