Ask Question
15 April, 16:02

Which of the following buffers will be most effective at pH 9.25? Group of answer choices a mixture of 1.0 M HC2H3O2 and 1.0 M NaC2H3O2 (Ka for acetic acid = 1.8 x 10-5) a mixture of 1.0 M NaCN and 1.0 M KCN (Ka for HCN = 4.9 x 10-10) a mixture of 1.0 M HCl and 1.0 M NaCl a mixture of 1.0 M NH3 and 1.0 M NH4Cl (Kb for ammonia = 1.76 x 1

+2
Answers (1)
  1. 15 April, 18:07
    0
    The most effective buffer at pH 9.25 will be a mixture of 1.0 M NH3 and 1.0 M NH4Cl

    Explanation:

    Step 1: Data given

    pH of a buffer = pKa + log ([A-]/[Ha])

    a mixture of 1.0 M HC2H3O2 and 1.0 M NaC2H3O2 (Ka for acetic acid = 1.8 x 10-5)

    pH = - log (1.8 * 10^-5) + log (1/1)

    pH = - log (1.8 * 10^-5)

    pH = 4.74

    a mixture of 1.0 M NaCN and 1.0 M KCN (Ka for HCN = 4.9 x 10-10)

    pH = - log (4.9 * 10^-10) + log (1/1)

    pH = - log (1.8 * 10^-5)

    pH = 9.30

    a mixture of 1.0 M HCl and 1.0 M NaCl

    The solution made from NaCl and HCl will NOT act as a buffer.

    HCl is a strong acid while NaCl is salt of strong acid and strong base which do not from buffer solutions hence due to HCl PH is less than 7.

    a mixture of 1.0 M NH3 and 1.0 M NH4Cl (Kb for ammonia = 1.76 x 10^-5)

    Ka * Kb = 1*10^-14

    Ka = 10^-14 / 1.76*10^-5

    Ka = 5.68*10^-10

    pH = - log (5.68*10^-10) + log (1/1)

    pH = - log (5.68*10^-10)

    pH = 9.25

    The most effective buffer at pH 9.25 will be a mixture of 1.0 M NH3 and 1.0 M NH4Cl
Know the Answer?
Not Sure About the Answer?
Find an answer to your question ✅ “Which of the following buffers will be most effective at pH 9.25? Group of answer choices a mixture of 1.0 M HC2H3O2 and 1.0 M NaC2H3O2 (Ka ...” in 📘 Chemistry if you're in doubt about the correctness of the answers or there's no answer, then try to use the smart search and find answers to the similar questions.
Search for Other Answers