July 16, 2019, 12:28:54 AM
Forum Rules: Read This Before Posting

### Topic: Solubility at Chemical Equilibrium  (Read 838 times)

0 Members and 1 Guest are viewing this topic.

#### platypus1234

• Very New Member
• • Posts: 1
• Mole Snacks: +0/-0 ##### Solubility at Chemical Equilibrium
« on: September 12, 2018, 06:12:55 PM »
Hello, I need help with a solubility problem, I am not looking for the answer just how I should go about solving.

Solubility product of CaCO3 at 25C is 2.5x10^-9

a) calculate the solubility of CaCo3 in pure water (mol/L and g/100mL)
b) Calculate the solubility of CaCo3 in a solution of 0.2M CaCl2 at 25C.
c) what is the ratio of SO42- to CO32- in a solution at equilibrium with CaSO4 and CaCO3?

For a) I got x= 6.7*10^-5 mol/L and 6.7*10^-4 g/100mL

I did this by
ksp=[Ca2+][CO32-]=[ x][ x]=4.5*10^-9
x^2=4.5x10^-9

and b) I got 2.3*10^-8 mol/L

I did this one by 0.2x=4.5*10^-9

I'm not confident on either of those answers, I just roughly followed the professors powerpoint and even if I did a and b correctly I dont understand why and I am lost on how I should even attempt c) Thank You
« Last Edit: September 14, 2018, 08:59:07 AM by Borek »

#### Borek ##### Re: Solubility at Chemical Equilibrium
« Reply #1 on: September 14, 2018, 09:05:07 AM »
So far so good (although in never hurts to explain what you mean by x and why).

For c you will need Ksp of calcium sulfate. If both salts are present, what ions does the solution contain? Is there any dependency between concentration of Ca2+ and concentrations of CO32- and SO42-?
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info