- #1

j3llzang

- 9

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## Homework Statement

When 50.0 mL of a 2.0 × 10

^{-4}M Ag

_{2}CrO

_{4}solution was added to 50.0 mL of a Na

_{2}CrO

_{4}solution a ppt formed (Ag

_{2}Cro

_{4}). What was the initial concentration of this Na

_{2}CrO

_{4}solution?

Ksp Ag

_{2}CrO

_{4}= 1.1 × 10

^{-12}

## Homework Equations

Given A

_{2 (aq)}+ B

_{(aq)}-> AB

_{(s)}

Ksp = [A]

^{n}

I tried using the "ICE" Table, but it didn't help:

Ag2CrO -> 2Ag + CrO4

I 2.0x10

C +x(?) -2x(?) -x(?)

E 2.0x10

I found [CrO4] at eqb using Ksp equation. (2.75x10

The initial [CrO4] was the [CrO4] from Ag2CrO4 plus Na2CrO4, right?

but why is it that [CrO4] at equilibrium is smaller than that of the initial [CrO4] in the initial Ag2CrO4 concentration?

Can anyone solve this problem???

Explanation would be nice :)

Thanks!!~

## The Attempt at a Solution

I tried using the "ICE" Table, but it didn't help:

Ag2CrO -> 2Ag + CrO4

I 2.0x10

^{-4}2.0x10^{-4}?C +x(?) -2x(?) -x(?)

E 2.0x10

^{-4}(unchanged) 2.75x10^{-5}I found [CrO4] at eqb using Ksp equation. (2.75x10

^{-5}M)The initial [CrO4] was the [CrO4] from Ag2CrO4 plus Na2CrO4, right?

but why is it that [CrO4] at equilibrium is smaller than that of the initial [CrO4] in the initial Ag2CrO4 concentration?

Can anyone solve this problem???

Explanation would be nice :)

Thanks!!~