Calculate the molar solubility of MX2 (Ksp=0.0000011) in 0.085 M NaX. Enter your answer as a decimal with two significant figures
I assume M is divalent and X is monivalent.
..........................MX2==> M^2+ + 2X^-
I........................solid.........0...........0
C.......................solid.........x...........2x
E........................solid........x...........2x
..................NaX==> Na^+ + X^-
I............0.085M.........0..........0.....
C...........-0.085........0.085.....0.085
E..............0............0.085.......0.085
Ksp = 1.1E-6 = (M^2+)(X^-)^2
Substitute the numbers.
(M^2+) from the above = x
(X^-) from the above = 2x from MX2 solubility and 0.085 from NaX so total is 2x + 0.085.
Ksp = 1.1E-6 = (x)(2x+0.085)^2
Solve for x = solubility of MX2 in mols/L.
To calculate the molar solubility of MX2 in 0.085 M NaX, we need to consider the solubility product constant (Ksp) and the concentration of NaX.
The general equation for the solubility product constant is:
Ksp = [M]^x [X]^(2x)
Where [M] represents the concentration of the metal ion M, [X] represents the concentration of the anion X, and x is the stoichiometric coefficient.
In this case, MX2 dissociates into M^2+ and 2X^- ions, so x is equal to 2.
We are given the value of Ksp, which is 0.0000011. To find the molar solubility, we need to determine the concentration of M^2+ ions.
Since MX2 dissociates completely, the concentration of M^2+ ions will be the same as the concentration of NaX, which is 0.085 M.
Now we can substitute the values into the equation:
0.0000011 = (0.085)^2 (2x)
Simplifying:
0.0000011 = 0.007225 (2x)
Dividing both sides by 0.007225:
0.0000011 / 0.007225 = 2x
0.000152 = 2x
Now, divide both sides by 2:
0.000152 / 2 = x
x = 0.000076 M
This value represents the concentration of M^2+ ions, which is the molar solubility of MX2 in 0.085 M NaX.
Therefore, the molar solubility of MX2 in 0.085 M NaX is 0.000076 M.