00 Sprint Wi-Fi 8:58 AM E\' 27% EO . Done 4 of 4 d)2 POIN NuS:at the point when
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00 Sprint Wi-Fi 8:58 AM E' 27% EO . Done 4 of 4 d)2 POIN NuS:at the point when 0.2 M Hpar is titrated 2 M NaOH (note that the total volume will increase) No Calculators Let the last digit of your id# A weak acid, HA, has a K, of If x=4.9=x K. = 1.0 x 10-1 1#x=0-3 y=x+3 K. = 1 x 107 (a) Determine the pH of a solution which is 0.1 M in HA and 0.1 M in NaA. (b) If 1.0 x 10 moles/L of solid NaA are added to the above solution, will the pH change be more, less or the same as if the NaA were added to a HCI or NaOH solution of the same pH? Explain in less than one sentence. A-B I J-L M NQ R-S T-Z October 26, 2009 there) at 6 tonight with Hae Jin Tomorrow at 5:30 with Jess 4 ]Explanation / Answer
pKa of acetic acid (HA)= 4.76
from Henderson-Hasselbach equation, pH= pKa+log[A-]/[HA]
[A-] is conjugate base of HA ( comves from NaA)
pH= 4.76+log (0.1/0.1)= 4.76
when NaA is aded, the new concentration of NaA= 0.1+1*10-3 =0.101
now pH= 4.76+ log (0.101/0.1)= 4.76
when HCl is added, it will be react wit the base and forming more HA. So [A-]/[HA] decreases and pH decreases
when NaOH is added, it will be react with HA forming more A- and ratio A-/HA increases and pH increases.
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