[mrummel]

Hey everybody, I have a test tomorrow on saturated solutions, K_sp, Q_sp and related stuff. There's a problem on the study guide that I'm having quite a bit of trouble with and need help. Any help would be appreciated, thanks

The Problem

In a saturated solution of silver carbonate the concentration of [Ag⁺] = 1.86x10^-4M

A) Calculate the concentration of the carbonate ion, CO₃^2- in this solution





B)Determine the K_sp of silver carbonate




C) Silver carbonate is allowed to reach equilibrium in a solution that contains 1.33 x 10^-3M AgNO₃

i. Using Lechatelier's Principle (arrows), show the effect that the silver nitrate has on the solubility of silver carbonate

ii. Calculate the solubility of silver carbonate in this solution

[UG]

A) Calculate the concentration of the carbonate ion, CO₃^2- in this solution

Can you write a balanced equation for the dissolution/dissolving of silver carbonate in water?

[mrummel]

A) Calculate the concentration of the carbonate ion, CO₃^2- in this solution

Can you write a balanced equation for the dissolution/dissolving of silver carbonate in water?

Yes, I'm pretty sure it would be Ag₂CO₃ 2Ag⁺ + CO₃^2-

[UG]

Ok good, so if you know the concentration of silver ions in the saturated solution, going from your equation then the concentration of CO₃^2- is?

[mrummel]

Ok good, so if you know the concentration of silver ions in the saturated solution, going from your equation then the concentration of CO₃^2- is?

Would it be 3.72x10^-4? Or do you square it? My teacher went over this really fast and I couldn't figure out how to do it.

[UG]

The concentration of CO₃^2- should be half that of the silver ions. Look at your equation again.

[mrummel]

The concentration of CO₃^2- should be half that of the silver ions. Look at your equation again.

Oh... Now I feel kind of stupid.

So the concentration is 9.3x10^-5

[UG]

Yes ok good, now for B, do you know how to write the K_sp equation? It is like any equilibrium type equation, use your chemical equation to help if needed.

[mrummel]

Yes ok good, now for B, do you know how to write the K_sp equation? It is like any equilibrium type equation, use your chemical equation to help if needed.

Yeah I have B, but C ii I don't know how to do. I've written this equation for C i.

AgCO₃  2Ag⁺ + CO₃^2-

AgCO₃ goes up, 2 Ag⁺ initially goes up, then down, and  CO₃^2- goes down. But how do I do ii?

[UG]

A good approximation you can make here is that the value of [Ag⁺] in your K_sp equation is equal to 1.33 x 10^-3, you can then work out the concentration of CO₃^2- and this will be the solubility of silver carbonate in 1.33 x 10^-3M AgNO₃