1) Determine the volume (in mL) of 0.539 M nitric acid (HNO 3 ) that must be add
ID: 532088 • Letter: 1
Question
1) Determine the volume (in mL) of 0.539 M nitric acid (HNO3) that must be added to 99.2 mL of 0.0403 M ammonia (NH3) to yield a pH of 8.49.
Assume the 5% approximation is valid and report your answer to 3 significant figures. A table of pKa values can be found.
2)Calculate the buffer ratio (base/acid) required for a buffer of pOH = 8.88 that is prepared by mixing propanoic acid and sodium propanoate. A table of pKa values can be found here. Report your answer to 2 significant figures in scientific notation.
Table 10.2: pKa and pKb values at 25 C for some common weak acids and their conjugate bases Acid formula pKa Conjugate base Acid name Conjugate base name pKl CCOOH CCOO trifluoroacetic acid 0.20 trifluoroacetate ion 3.80 CI CCOOH 0.66 Cl3CCOO trichloroacetic acid trichloroacetate ion 3.34 HOOCCOOH 1.23 HOOCCOO oxalic acid hydrogen oxalate ion 12.77 dichloroacetic acid ClaHCCOOH 1.30 CI H CCOO dichloroacetate ion 12.70 sulfurous acid H2SO3 (HOSOOHj HSO. 1.77 hydrogen sulfite ion 12.23 hydrogen sulfate ion HSO, 1.92 SO sulfate ion 12.08 chlorous acid HCIO. 1.95 CIO. chlorite ion H PO. H PO phosphoric acid 2.12 hydrogen phosphate ion 11.88 chloroacetic acid CIH CCOOH 2.87 CIH CCOO chloroacetate ion 1.13 bromoacetic acid BrH CCOOH BrH CCOO bromoacetate ion 2.90 1.10 actic acid HE OCOOH 3.08 C2H5 ocoo lactate ion 0.92 2 H50 (COOH) 3.13 C3H50 (COOH) COOT dihydrogen citrate ion 0.87 citric acid 3 fluoride ion CaHTO COOH acetylsalicylate ion formate ion 5 7 4 COOH C5H7O4 COO ascorbic acid 4.10 ascorbate ion 9.90 hydrogen oxalate ion HOOCCOO OOCCOO 4.19 oxalate ion 9.81 4.20 C6Hscoo benzoic acid C6H5 COOH benzoate ion 9.80 C6H5NH 4.63 C6H5NH phenyl phenyl 9.37 ammonium ion amine (an neExplanation / Answer
Its an example for basic buffer and it needs pKb of NH3 and formula for pH= 14-pOH
pOH = pKb+log [initial concentration of salt x initial volume of salt /initial concentration of base]
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