A chemistry graduate student is given 300.mL of a 0.70M pyridine C5H5N solution. Pyridine is a weak base with Kb=1.7*10^

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A chemistry graduate student is given 300.mL of
a 0.70M pyridine C5H5N solution. Pyridine is a
weak base with Kb=1.7*10^−9. What mass
of C5H5NHCl should the student dissolve in
the C5H5N solution to turn it into a buffer
with pH =4.70? You may assume that the volume of the
solution doesn't change when the C5H5NHCl is dissolved in
it. Be sure your answer has a unit symbol, and round it to
2 significant digits.