## Need help with analytical chemistry Ques

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Saira_Ashraf
Newbie
Posts: 1
Joined: Thu Aug 29, 2019 12:12 am

### Need help with analytical chemistry Ques

I am trying to solve this question but in vain if anyone can explain it will be great.

Q: Calculate the solubility of the solutes Th(OH)4 for solution in which the cation concentration is 0.050M.

I found the Ksp which is 1.1*10^-15 and i solved it this way :-

[Th+]+[4OH-]=1.1x10^-15
4[OH]= 4âˆš1.0*10^-15 = 1.8x10^-4
1/4(1.8*10^-4)
=4.5x10^-5 = Final Ans

I have an exam and i am struck with this question pls tell me what is my mistake?
ChenBeier
Distinguished Member
Posts: 742
Joined: Wed Sep 27, 2017 7:25 am
Location: Berlin, Germany
You have mistypings.

Kl = [Th4+] * [(OH-)^4]

Th = x , OH- = 4x

Kl = x* (4x)^4

Kl = 256 * x^5

x =5âˆš (Kl/256)

x = 5âˆš(1.1 * 10^-15/256)

x = 3,36 * 10^-4

OH- = 4*x

OH- = 1,34 * 10^-3 mol/l