Question

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1. (3 pts) Calculate the pH of a buffer prepared by mixing 4.0 g OT IN uffer prepared by mixing 4.0 g of NH CI with 29 mL of OM N3 and diluting to 1.00 L (a) neglecting activity and (b) including activity. (Hint: see Eqn 9-18 in your text) (answers = 10.00; 10.11) pH = pka + log [A-JA- THAI VAH bowy 2. (3 pts) Calculate the percent relative error in solubility of CaF2 in 0.10 M NaNO3 when activity is neglected in the calculation. (-38%)

Answer 1

Jonic strength of the solution IEEc; z;"...() here, a 42 are concentration & valency of ith species,& Here inolar man of whyll & 53.4938 in number of most of Hyll in gogot NH4Cl = 410g & mot & 0.075 mol 53.4919 solution in diluted to det fall – 0.075 mol mol = 0.075 m NAylt fully dissociates So, Caityt – Car - 0.0750 & I - 45 Catert. Zotit. & Can. 2017? = x [ 01075 x + 0.075 X (-1313 = 0.675

Now, in solution. Mit & Vita . Certen & - 148 in x 0.01944 ル人 MNH in 0.98 m .me = Molarity of with 214.8M VNikevol. of Nih = 29mm = 0.0280) Here, Hyt dissociates an. that H & NH3 the carili briven contant agt . anthy 6 akere, a = betivity Ra & anhu 2 Ct. CNt. fr .ft or, ka = Cartut fritt A.= conconsration concour 60,9 x activity . Coefficines for ithe species Now relation of ionic strength (I) & activity coefficient (f) log fi. – 6.5) ze so I i & activity coefficiers of where, fi - ist pelier; th espeuer Zir values of ith spener log fruit -0.51 (+15 50075 = – 0.14 en fri - 10-014-072 D

(2) when activity neglected then a nc open canation (ii) leccomer & Capt. C Nith ka= Catat CATX 043 7 5.6410-10 - 0.075 0143 i Car= 5.6410-10 x 0.875 pH = -log, (5.77X10"") 8.77x10-1 From = 10:01 1001 .: PH neglecting activily is m y to) when activity is not regheted. then, veing equation (iii) 56x10-10 - Cat. Cart fr. frit Caitut 256x10-10 = (CA+ x A). Caitty Lene folket There, CNHut for dilulê solution 072 - Cotut Inity for ditute & 5681510 - (at 043, 0.075 te tot=1) i auto 5:6X/090 78.075X8-72 Cfnment = 0.227 ♡ aute 703x10-11 a = 4 x 1 Here, petit log apr an log (7:03 8101) 110 .: Pr when activity included then it is 10.15 0.43 dio V10 - 10.15