[Traumatic Acid]

Hi all
I'm going to apologise in advance because I'm an incredibly lost seal.
The question I am working on is:

Silver sulfate, Ag2SO4 (molar mass = 311.87 g/mol), has Ksp = 6.0 × 10^–5. What mass of Ag2SO4 will dissolve per litre of water?

My attempt:

AgSO4 (aq)  ===> Ag+    + SO4-

Ksp = [Ag+] [SO4-] = (x) (x) = x² = 6.02 x 10^-5
x = √(6.0 X 10^-5) = 7.7 x 10^-3 mols AgSO4

From there it is easy to convert it to grams. Annoyingly enough I was never given an answer to this question so I don't know if I'm even close. If I'm wrong could anyone please show me the correct way to calculate this?
Much appreciated
- Traumatic Acid

[Corribus]

First, indicate units as often as you can. You will catch many errors this way.

Second, if your reaction equation isn't right, you've no hope to get a correct answer. Did you not notice a discrepancy between the formula for silver sulfate you provide in the beginning of the problem and the formula you use in your reaction equation?

Success in general chemistry relies in large part upon carefulness and attention to detail. Write your units, use good formatting (subscripts and superscripts), and be careful with your reaction equations - do they make sense, and are they consistent throughout the workup of your problem. Start there, and then we can see if the conceptual approach falls into place.

[Traumatic Acid]

Hi there,
Thanks for your reply.

Wow, didn't even notice it was Ag2SO4.

Attempt 2:
Silver sulfate, Ag2SO4 (molar mass = 311.87 g/mol), has Ksp = 6.0 × 10–5. What mass of Ag2SO4 will dissolve per litre of water?

Ag2SO4 ---> 2Ag⁺ + SO4^-

Ksp = [Ag⁺]² + [SO4^-]
Ksp = (x)²(x) = x³
x = ∛6.0 x 10^-5
x = 0.039 mol / L
311.87 x 0.039 = 12.16 grams Ag2SO4 can dissolve in one liter of water.

Better?

[Borek]

Ksp = (x)²(x) = x³

That would mean [itex][Ag^+] = [SO_4^{2-}][/itex], is it possible?

[Traumatic Acid]

Got the darn thing!

Ag2SO4 ----> 2Ag + SO4

Ksp = [AG⁺]² [SO4 ^-]
= (2 x)² (x) = 4x² = 6.0x10^-5
x = ∛((6.0 x 10^-5 )/4) = 0.0246621
311.87 x 0.0246621 = 7.79 g will dissolve in 1 L of water

I did end up finding the answer yesterday, and it's 7.9 grams. I think considering all the decimals my answer is alright. But how would one calculate exactly 7.9?

[Borek]

No way to get 7.9, 7.69 g is a correct answer (your 7.79 seems to be a typo).

[Traumatic Acid]

Awesome!
Thanks for your help that question was doing my head in!

- Traumatic acid