One of the best buffer choice for pH = 8.0 is Tris with Ka value of 6.3 x 10^-9.
To support this answer, we first calculate for the pKa value as the negative logarithm of the Ka value:
pKa = -log Ka
For Tris, which is an abbreviation for 2-Amino-2-hydroxymethyl-propane-1,3 -diol and has a Ka value of 6.3 x 10^-9, the pKa is
pKa = -log Ka
= -log (6.3x10^-9)
= 8.2
We know that buffers work best when pH is equal to pKa:
pKa = 8.2 = pH
Therefore Tris would be a best buffer at pH = 8.0.
The Large intestine absorbs water and vitamin K from digested food.
if you have 1.27*10^-36= [Cu2+][X2-] then you can set both those values equal to x because they're stoichimetrically equal.
1.27*10^-36=x^2
Take the square root of both sides.
1.13*10^-18=x
That would be your solubility.
