Question

Please help! I'm trying to find the solubility of Ca(OH)2 in .001305 mol/L aqueous NaOH?

Saturated solution of Ca(OH)2 in 0.01305 mol/L NaOH.
[HCl] = 0.1213 M
Volume of HCl = 9.81 mL
Volume of Ca(OH)2/NaOH aliquot = 25ml

Find:
1. the TOTAL [OH-] in the saturated solution of Ca(OH)2 in NaOH
2. the [OH-] due to dissolved Ca(OH)2
3. determine the solubility of Ca(OH)2 in the NaOH solution
4. the Ksp for Ca(OH)2 for the saturated solution of Ca(OH)2 in NaOH

Answer 1

http://www.jiskha.com/display.cgi?id=1489957110

Answer 2

Im still unsure of how to find #3 and #4, is the solubility the same for CaOH2 to NaOH :/?

Answer 3

When they multiplied concentration of NaOH with the total volume wouldn't that give you moles? That part is confusing to me, I'm unsure what to do next.

Answer 4

I believe for #3 the solubility for CaOH2 in NaOH would just be the Ca ion. But im unsure as of how to calculate it.
And for 4,Ksp for Ca(OH)2 is (Ca^+2)(OH^-)^2; im unsure of this too.
I think we have to wait for drbob to check this out for us.

Answer 5

Thanks, and for the #1 how do we get the [oh-] of Naoh to add to the total?

Answer 6

I'll try to take care of both questions but it may be confusing to try t answer both with one post.
For #3, yes, solubility Ca(OH)2 is (Ca^2+). You have total OH and you have OH from the NaOH. The difference is the OH from the Ca(OH)2 itself. 1/2 the OH from Ca(OH)2 gives the Ca^+ and that will be the solubility CaCO3 in mols/L. Convert that to grams if you wish but you will need it in M for #4. Where did the 1/2 come from? That's Ca(OH)2 ==> Ca^2+ + 2OH^- so (Ca^2+) is 1/2 (OH^-).
For #4, Just plug in the numbers.
Ksp = (Ca^2+)(OH^-)^2
You know Ca^2+ and you know OH^-, solve for Ksp. :-).

For Alex, yes M x L = mols. I almost never change out of mols when I work these things until I get to the final answer, then convert to the units the problem wants. For #1, M NaOH x L NaOH on the initial sample gives you TOTAL MOLS OH.

Answer 7

So basically take the [OH-] of caoh2, and divide it by 2 and we get [ca2+]?

Answer 8

Yes. Isn't that what the equation says?
Ca(OH)2 ==> Ca^2+ + 2OH^-
So if you know the OH from Ca(OH)2 then 1/2 that is Ca^2+. By the way you should write Ca(OH)2 right; the way you write it is not right and I know what it is only because I've been working with the problem.

Answer 9

Thank you guys sooooooo much! You are really helpful!

Answer 10

Thanks a lot sir. And yes i will make sure to write it correctly next time

Answer 11

PLEASE HELP! Consider the following galvanic cell: Ag(s) | Ag+(aq) || Cu2+(aq) | Cu(s)?

Match the components with their function in the cell.


1. |

2. ||

3. Ag(s) | Ag+(aq)

4. Cu2+(aq) | Cu(s)


A. Cathode Half Reaction

B. Phase boundary

C. Salt Bridge

D. Anode Half Reaction