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anonymous
 one year ago
For hydrocyanic acid, HCN, Ka = 4.9 × 1010.
Calculate the pH of 0.20 M NaCN.
What is the concentration of HCN in the solution?
for the ph i got 10 is that right?
anonymous
 one year ago
For hydrocyanic acid, HCN, Ka = 4.9 × 1010. Calculate the pH of 0.20 M NaCN. What is the concentration of HCN in the solution? for the ph i got 10 is that right?

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anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i did 4.9^10 multiplied it times 0.20 and then i took the square root

aaronq
 one year ago
Best ResponseYou've already chosen the best response.1You have to always look at what you're given. They gave the pKa for HCN but the solution used was NaCN, the conjugate base of HCN. The solution is acting as a base: \(\sf NaCN+H_2O\rightleftharpoons NaOH+HCN\) and you use the Kb, \(\sf K_B*K_A=K_W\) The expression is: \(\sf K_B=\dfrac{[NaOH][HCN]}{NaCN}\) By using I.C.E. table you arrive at: \(\sf [NaOH]=\sqrt{K_B*[NaCN]}\) Find pOH, then pH (note: pH+pOH=14) Also, \(\sf [HCN]=[NaOH]\)
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