140 mg of KN3 is dissolved into 3.5l of water what is the ph of the solution?
I got 2.76. I think i may need to subtract the value from 14 to get the true pH or is 2.76 the true pH?
Any details on the matter are greatly appreciated.
This is all the information given in the question.
I did concentration = moles/vol
then used the concentration to find the pH with pH=-log[concentration]. Is that Wrong?
we have
140 mg of KN3 is dissolved into 3.5l of water
mole of KN3 = mass / molar mass = 0.140 g / 81.1184 g/mole = 1.726 * 10^-3 mole.
and
concentration of KN3 = 1.726 * 10^-3 mole / 3.5 L= 4.931 * 10^-4 M
pKa of HN3 is 4.63.
Here
salt hydrolysis occurs.
It is the salt of strong base and weak acid.
Using
pH = 1/2 * [PKw + pKa + log C]
or
pH = 1/2 * [14 + 4.63 + log (4.931 * 10^-4 )]
or
pH = 7.66
140 mg of KN3 is dissolved into 3.5l of water what is the ph of the solution? I got 2.76. I think i may need to subtract...
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