Imidazole (C3H4N2, FM 68.08) is a weak base with pKb = 7.01. You wish to make 250.0 mL of a  0.300 M buffer at pH 7.50. You can use one of two methods.  a. First, starting with imidazole and imidazole hydrochloride, what mass of each would you need to  combine and dilute to 250.0 mL to create your buffer?    b. Now, starting instead with imidazole and 0.500 M HCl, what mass of imidazole should you use, and  approximately how many milliliters of HCl will you need to add (before diluting to a final volume of  250.0 mL with water)?  c. Of the two methods, which one is preferable and why?

E www-awu.aleks.com/alekscgi/x/ O ACIDS AND BASES Calculating the pH of a weak base titrated with a strong acid An analytical chemist is titrating 93.8 mL of a 0.6300M solution of piperidine (C5H₁NH) with a 0.07100M solution of HNO3. The pK, of piperidine is 2.89. Calculate the pH of the base solution after the chemist has added 986.9 mL of the HNO3 solution to it. Note for advanced students: you may assume the final volume equals the initial volume of the solution plus the volume of HNO3 solution added. Round your answer to 2 decimal places. pH = Explanation 66°F Partly sunny Check X S Q Search AS B W UNDER © 2023 McGraw Hill LLC. All Rights Reserved. Terms of Use | Privacy Ce CEREDARE FR X

Part A Suppose you wanted to make a buffer of exactly pH 7.00 using KH₂PO4 and Na2HPO4. If the final solution was 0.21 M in KH₂PO4, what concentration of Na₂HPO4 would you need? (pKą for H3PO4, H₂PO4¯¯, and HPO are 2.14, 6.86, and 12.40, respectively.) 2- Express your answer to two significant figures. Π| ΑΣΦ ? M

Solution    :                  Acetic Buffer                                NaCl Original pH      :               4.2                                                7.2 pH after adding 5 drops of HCl     :  4.2                           2.7 pH after adding 5 drops of NaOH   :  4.2                         11.1 Which sample showed little or no change in pH upon the addition of acid and base? Please write an equation and explain briefly.