Question

In a solution with a concentration of 0.0125 M in Ag⁺, calculate the concentration of PO₄³⁻ when Ag₃PO₄ starts to precipitate.

a) 0.0125 M
b) 0.00625 M
c) 0.00417 M
d) 0.01875 M

Answer 1

To find the concentration of
`(PO_4)^{3-` when
`Ag_3PO_4` starts to precipitate in a 0.0125 M Ag+ solution, we use the Ksp value for
`Ag_3PO_4`. The Ksp expression for
`Ag_3PO_4` is Ksp =
`[Ag+]^3[(PO_4)^( 3-)]`. With the Ksp value and given Ag+ concentration, we can solve for [
`PO_4`3-].

To calculate the concentration of
`(PO_4)^{3-` when
`Ag_3PO_4` starts to precipitate from a solution that is 0.0125 M in Ag+, we need to use the solubility product constant (Ksp) for
`Ag_3PO_4`.

The chemical equation for the dissolution of
`Ag_3PO_4` is:

`Ag_3PO_4`(s) ⇌ 3Ag+(aq) +
`(PO_4)^{3-`(aq)

The Ksp expression is:

Ksp =
`[Ag+]^3[(PO_4)^( 3-)]`

Given the Ksp for
`Ag_3PO_4`, we can plug in the concentration of Ag+ and solve for the concentration of
`(PO_4)^{3-`.

Let's assume the Ksp for
`Ag_3PO_4` is 'x'. The concentration of Ag+ is already given as 0.0125 M. Since there are 3 moles of Ag+ for each mole of
`Ag_3PO_4` that dissolves, the concentration of Ag+ ions will be three times the concentration of
`(PO_4)^{3-` ions. Therefore, we set up the equation as follows:

Ksp =
`(0.0125)^3`[
`(PO_4)^{3-`]

x =
`(0.0125)^3`[
`(PO_4)^{3-`]

To find the concentration of
`(PO_4)^{3-`, we divide both sides by
`(0.0125)^3`:

[
`(PO_4)^{3-`] = x/
`(0.0125)^3`

Without the actual Ksp value, we cannot provide the exact concentration, but this is the process that would be used to calculate it. Once Ksp is known, we can plug it in and solve for [
`(PO_4)^{3-`].

If we assume the Ksp for
`Ag_3PO_4` is a known value, it's possible to directly calculate [
`(PO_4)^{3-`], but since it hasn't been provided, we cannot complete the calculation.