Ask Question
6 October, 05:09

Find the pH of 0.135M NaCN solution. For HCN, Ka=4.9⋅10-10,

+4
Answers (1)
  1. 6 October, 05:27
    0
    NaCN is considered as salt of weak acid (HCN) and strong base (NaOH):

    we have salt concentration Cs = 0.135 M NaCN and Ka = 4.9 x 10⁻¹⁰

    use this formula to calculate pH:

    pH = 1/2 pKw + 1/2 pKa - 1/2 pCs

    pKw = - log Kw, pKa = - log Ka and pCs = - log Cs

    pKw = - log (1 x 10⁻¹⁴) = 14

    pKa = - log (4.9 x 10⁻¹⁰) = 9.31

    pCs = - log (0.135) = 0.87

    pH = (1/2 x 14) + (1/2 x 9.31) - (1/2 x 0.87) = 11.22

    Note that it is basic solution (pH more than 7) because it consists of strong base and weak acid
Know the Answer?
Not Sure About the Answer?
Find an answer to your question 👍 “Find the pH of 0.135M NaCN solution. For HCN, Ka=4.9⋅10-10, ...” in 📗 Chemistry if the answers seem to be not correct or there’s no answer. Try a smart search to find answers to similar questions.
Search for Other Answers