1.
Calculate the approximate pH of the following aqueous solutionsat 25C. (Note: consider one decimal place for the pH answer.)
a) H3PO4 (0.20 M),(pKa1=2.15, pKa2=7.15,pKa3=12.38)
b) Na2CO3 (0.20 M),(pKaH2CO3/HCO3? = 6.35, pKaHCO3?/CO32? =10.30)
c) NaHCO3 (0.20 M) (use pKa values from part \"b\"above)
a
b
c
2.
Calculate the approximate pH of the following aqueous solutionsat 25C. (Note: consider one decimal place for the pH answer.)
a) NH4Cl (0.20 M) + CH3COONa (0.40M) ,(pKa NH4+/NH3= 9.24,pKaCH3COOH/CH3COO?= 4.76)
b) NH3 (0.040 M)+ NaOH (0.040M)
a
b
3.
Calculate the approximate pH of the following aqueous solutionsat 25C. (Note: consider one decimal place for the pH answer.)
a) H2S (0.10 M) + H3PO4 (0.20M), (pKaH2S/HS? = 7.02,pKa HS?/S2? = 13.99, andH3PO4 pKa valuesare given in part \"a\" of question 1)
b) H3PO4 (0.20M) +NaH2PO4 (0.10 M) (use pKa values given inquestion 1)
c) NH4H2PO4 (0.1 0M) (pKavalues are given in question 1 and 2 )
a
b
c
4.
A chemist prepares a solution that contains a formalconcentration of 0.5 M phthalic acid and that has a pH of 2.88.What is the approximate fraction of phthalic acid in this solutionat 25 C? Use 1 sig figs for the answer
Phthalic Acid:HOOCC6H4COOH/HOOCC6H4COO-pKa1 = 2.95,HOOCC6H4COO-/-OOCC6H4COO-pKa2 = 5.41
Bonus: For more practice find the fractions of other species(forms) at this pH and decide which one is the predominant form.Plot an approximate curve of alpha vs pH for each species. You canhand them in for extra credit.
5.
How many grams of Ba(IO3)2 (FW=487 g/mol)can be dissolved in one liter of the following solutions at 25C?(Ba(IO3)2Ksp=1.57x10?9)Use three significant figures for the answer. You do not need toconsider the effect of electrolyte.
a) In water.
b) In a solution of Ba(NO3)2 (0.0700M)
a
b
6.
If a 0.100 M solution of NaOH is added to a solution containing0.200 M Ni2+, 0.200 M Ce3+, and 0.200 MCu2+, which metal hydroxides will precipitate first andlast, respectively? Ksp for Ni(OH)2 is6.0x10?16, for Ce (OH)3 is 6.0 x10?22, and for Cu(OH)2 is4.8x10?20.
A) Ni(OH)2 first, Cu(OH)2 last
B) Cu(OH)2 first, Ni(OH)2 last
C) Ni(OH)2 first, Ce(OH)3 last
D) Cu(OH)2 first, Ce(OH)3 last
E) Ce(OH)3 first, Cu(OH)2 last
Give detailed explanation
