if the pKa of HCN is 9.21,what it its Ka?

pKa = -log Ka

To find the Ka of a weak acid, you can use the equation Ka = 10^(-pKa). In this case, the pKa of HCN is given as 9.21. Therefore, to find its Ka, we can use the equation:

Ka = 10^(-pKa) = 10^(-9.21)

Using a calculator, we can calculate the value of Ka:

Ka ≈ 1.4 x 10^(-10)

Therefore, the Ka of HCN is approximately 1.4 x 10^(-10).