Question

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How many milliliters of 0.244 M HNO3 should be added to 214 mL of 0.00668 M 2,2'-bipyridine hydrochloride to give a pH of 4.16? (Assume pka = 4.34 and Kw = 1.01% 10-14) 49 3.9 x mL

Answer 1

= Ja 6rdeto decrease the pt of the Soludion NDbipyridine) to 4-6 we nad to add a stongacid (enb resulting a HA Lseak aad). 6n the pduct Side he equatiDg The enuatron Can be witen as filows : Pa+ log Use Hassel bach Henderson eguation pH Substitute tnese v alnes n4u eg nakbn above and Stve fr x, pu winaetthe answes. 4-16E 4 34 log ly5x where ptt Q.1 pka 4.3 A(0.0 0145-X HB the acid tohere HND3 -018 A t We are given dy mL f 0 00668 N 6 A 0.0 0145-メ weak aud Conveat Hip to moles Melarity can) Where M = 0. D0668 0-0olu o.66 V V= 0.q!yL m:MメV nubag of meles (we ned to find tuis) - 0-00145ーメ m 0-00 668x0 214000145 medes 6.00087 mdes O-o0lyS Somolesf 0.00I45 MOleg Now, use ts * ensout the mole chang e inte ran Cwe knos XHAJ = TH HA Initial holes f)the Song acid HNa So ND,ned ed 0.00087moles o.601ly5 X tinal moles -x) Gome&t tas to mL moles х whure M o-Q44 -DD087 lit = do0087/103m males Vofume males Vfume -ml z 3.5}mL 6 249 ০२५५ So, we need 3 57mL of 0244MHNO M bving the pH to 4-16