A chemistry graduate student is given of a dimethylamine solution. Dimethylamine is a weak base with . What mass of should the student dissolve in the solution to turn it into a buffer with pH ? You may assume that the volume of the solution doesn't change when the is dissolved in it. Be sure your answer has a unit symbol, and round it to significant digits.

This is an incomplete question, here is a complete question.

A chemistry graduate student is given 500 mL of a 0.20 M 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 = 4.76 ?

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.

Answer : The mass of C₅H₅NHCl is, 34 grams.

Explanation :

First we have to calculate the value of .

The expression used for the calculation of is,

Now put the value of in this expression, we get:

Now we have to calculate the value of

Now we have to calculate the concentration of C₅H₅NHCl.

Using Henderson Hesselbach equation :

Now put all the given values in this expression, we get:

Now we have to calculate the mass of C₅H₅NHCl.

Now put all the given values in this formula, we get:

Thus, the mass of C₅H₅NHCl is, 34 grams.