# 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)

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Buffer concept. You can view video lessons to learn Buffer. Or if you need more Buffer practice, you can also practice Buffer practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Woldman's class at FSCJ.