Which of the following is NOT a true statement?
2 answers:
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Answer:
a) pH will be 12.398
b) pH will be 4.82.
Explanation:
a) The moles of NaOH added = molarity X volume (L) = 2 X 0.01 = 0.02 moles
The total volume after addition of pure water = 0.780+0.01 = 0.79 L
The new concentration of /NaOH will be:
the [OH⁻] = 0.025
pOH = -log [OH⁻] = 1.602
pH = 14 -pOH = 12.398
b) The buffer has butanoic acid and butanoate ion.
i) Before addition of NaOH the pH will be calculated using Henderson Hassalbalch's equation:
pKa=
ii) on addition of base the pH will increase.
Explanation:
The given reaction is as follows.
Initial : 0.160 0.160 0
Change : -x -x 2x
Equilibrium: 0.160 - x 0.160 - x x
It is given that = [0.160 - x] = 0.036 M
and, = [0.160 - x] = 0.036 M
so, x = (0.160 - 0.036) M
= 0.124 M
As, [HI] = 2x.
So, [HI] =
= 0.248 M
As it is known that expression for equilibrium constant is as follows.
=
= 47.46
Thus, we can conclude that the equilibrium constant, Kc, for the given reaction is 47.46.