Question

4. (15 points) A solution that is 0.500 M HF and 0.240 M NaOH reacts to produce a mixture with what pH? The pKa of HF is 3.20. Hint: This is two reactions. The first involves a strong base with a weak acid -it will be quantitative. The second is an equilibrium reaction, the winner of the first reaction reacts with water. The second gives you the pH.
Please explain, thank you.

Answer 1

0.24 co -H F + Naon Na F +4₂0 6.50 0.24 This is a acidic Orso -0.24 o पिfer Sector the strong Base is not present in the soil, but the weak acid of its conjugat only present in the Sol & by the Basic 'Buffer soll it is a Acidic Buffer HANG so weakecid is conjugate, Weakącid

qh = pk + dag skall} pt 3.20 + logo2.14 0.24 0.5-0.14 = 3,20 + Tog 0:24 0.26 PM = 3.20 + lsyo.92 P" = 3.200 0.03 [ph = 3.17) - - 1. 2 7 x la sol MX - ks P = 1.2.7610-36 In pure water Mx - Mt + x - * s mtJ8-1 = ksp = sxs g 1.27X10-30 = 2 - s-J1 27x10-36 -) S = | | 2x Fol 4 In 0-25 MB92 MX - . Mt + x Sto.25 s due to common icon effecti .25 MBS, mtha Be 0.25 0.25 2x0.25 Ksp = [ + ][ + ] 0.25 $25

To 27 XI-36, because neglect the - без релл •gs] 1.27 x 1036 - sxo.25- SESE 127 X1036 0. 25 s e 5.08x10-36 M