1) it is found that .30 M solutions of the three shots Na3X, Na2Y and NaZ have pH's of 8.5, 7.0 and 10.5 not necessarily in order. (X,Y, and Z AE anions. Na is sodium ion)

Question

A) explain how anions can act as bases in aqueous solution. Write a chemical equation to explain your answer.
B) which pH most likely goes with which salt. Explain.
C) what is the approximate pH of a .010M solution of HZL explain your reasoning.
D)Calculate the acid dissociation constants, Ka for each of the acids, HX-2, HY-, and HZ, and rank them in order of increasing strength, the weakest first. Justify your answer.

Answer 1

a. X^- + HOH ==> HX + OH^-
The anion hydrolyzes with water producing OH^- ions which is why they are basic.

b.
.....X^- + HOH ==> HX + OH^-. For 0.3M
I...0.3.............0.....0
C....-y.............y.....y
E...0.3-y...........y.....y
Kb for X,Y, or Z = (Kw/Ka for HX, k2 for H2X and k3 for H3X)
Therefore, smaller Ka, k2, or k3 values lead to larger Kb values.
Kb = (y)(y)/(0.3-y)
Thus smaller k1, k2, k3 values lead to larger Kb values and that leads to higher values of y when the above equation is solved. y = OH^- in this case, so larger OH^- values means more OH which is smaller H^+ and larger pH values.

c.
I have no idea what HZL is.
d. Go through the calculation I show for part B, then Kb = Kw/Ka where Ka = Ka for HZ, k2 for H2Y and k3 for H3X,