Problem: Which combination is the best choice to prepare a buffer with a pH of 9.0?a) NH3; NH4Cl (pKb for NH3 is 4.75)b) C5H5N; C5H5NHCl (pKb for C5H5N is 8.76)c) HNO2; NaNO2 (pKa for HNO2 is 3.33)d) HCHO2; NaCHO2 (pKa for HCHO2 is 3.74)

FREE Expert Solution

buffering range:              pH = pKa ± 1


a) 

pKa = 14 – 4.75 = 9.25

buffering range: pH = 8.25 to 10.25


b)

pKa = 14 – 8.76 = 5.24

buffering range: pH = 4.24 to 6.24


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Problem Details

Which combination is the best choice to prepare a buffer with a pH of 9.0?
a) NH3; NH4Cl (pKb for NH3 is 4.75)
b) C5H5N; C5H5NHCl (pKb for C5H5N is 8.76)
c) HNO2; NaNO2 (pKa for HNO2 is 3.33)
d) HCHO2; NaCHO2 (pKa for HCHO2 is 3.74)

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