If two salts AX and BX2, have the same Ksp values of 4.0x10^-12 at a given temperature, then
A. their molar solubilities in water are the same
B. the salts are more soluble in 0.1 M NaX than in water
C. the molar solubility of AX in water is less than that of BX2
D. addition of NaX will not affect the colubilities of the salt.
well C says AX is less than BX2 and it is so i thought it would be that one.
That's right.
To determine the correct answer, we need to understand the concept of the solubility product constant (Ksp) and how it relates to the molar solubility of salts in water.
The Ksp represents the equilibrium constant for the dissolution of a sparingly soluble salt in water. It is a measure of the solubility of the salt in water and is calculated by multiplying the concentrations of the ions raised to their stoichiometric coefficients.
Let's analyze the given options:
A. Their molar solubilities in water are the same.
This option assumes that the molar solubility of AX and BX2 is the same. However, we cannot conclude this based solely on having the same Ksp value. The molar solubility depends on the stoichiometry of the salt and cannot be determined solely from Ksp. Therefore, this option is not necessarily true.
B. The salts are more soluble in 0.1 M NaX than in water.
The addition of an additional common ion (Na+) would decrease the solubility of the salt because of the common-ion effect. Therefore, this option is unlikely to be true.
C. The molar solubility of AX in water is less than that of BX2.
This option suggests that the salt with the lower stoichiometry (AX) has a lower molar solubility. Since the stoichiometry of AX is 1:1, and the stoichiomtry of BX2 is 1:2, we can infer that AX has a higher molar solubility. Therefore, this option is not true.
D. Addition of NaX will not affect the solubilities of the salt.
This option is the most likely to be true. When NaX is added to a solution, the concentration of X- ions increases due to the dissociation of NaX. However, since the addition of NaX does not change the Ksp value of AX or BX2, the solubility of the salts remains the same. Therefore, adding NaX does not affect the solubilities of the salts AX and BX2.
In conclusion, the correct option is D. Adding NaX will not affect the solubilities of the salts.
which do you think is correct and why? I suggest you make up problems and work each one; for example, see if A is a true statement.
AX ==> A^+ + X^-
Ksp = (x)(x) = 4 x 10^-12
x= sqrt 4 x 10^-12 = 2 x 10^-6 M
AX2 ==> A^+2 + 2X^-
Ksp = (x)(2x)^2 = 4 x 10^-12
4x^3 = 4 x 10^-12
x = 1 x 10^-4 M
So they are not the same and A is not true. ETC. For the common ion in B, just use 0.1 M NaX.