For a triprotic acid H2PO4. Ka1=7.11e-3, Ka2=6.32e-8 and Ka3=7.1e-13. 50mL each of 0.05F CaCl2 and 0.05F phosphoric acid were mixed. Ksp CaHPO4=2.6e-7.
a) Would CaHPO4 precipitate when phosphoric acid and calcium chloride were mixed together?
b) List all species (ions, molecules, solids etc) expected to be present in the system.
c) Write the set of equations that can be used to solve for the concentrations of all the species in the system.
Thank you in advance for your help :)
Didn't I do one of those "list all species of H3PO4" for you recently? I don't want to write all of that stuff again. Look at your notes (you do take notes here I would think). What can you do on your own?
No, I am sorry. This is the first time I have posted this question. Where can I find the similar question?
I found it.
http://www.jiskha.com/display.cgi?id=1425612744
Thank you for your help. I think the differences between my question and the question that you sent me is that: mine is the mixture of H3PO4 and CaCl2 while the other is just dissociation of H3PO4. For b) I just write H3PO4 + H20 -> H2PO4- +H3O+
H2PO4- +H20 -> HPO4- +H3O+
HPO4 2- + H2O -> PO43- +H3O+
So what should I write for the reaction between H3PO4 and CaCl2
i am still having issues setting this exact problem up can you please help
To determine whether CaHPO4 would precipitate when phosphoric acid and calcium chloride are mixed together, we need to compare the reaction quotient Qsp to the solubility product constant Ksp.
a) To find the concentrations of all the species in the system, we need to consider the dissociation of the triprotic acid, the reaction between CaCl2 and phosphoric acid, and the solubility equilibrium of CaHPO4. Let's go step by step.
b) Species present in the system:
- H2PO4- (dissociated form of phosphoric acid)
- HPO42- (dissociated form of phosphoric acid)
- PO43- (dissociated form of phosphoric acid)
- Ca2+ (from CaCl2)
- Cl- (from CaCl2)
- CaHPO4 (precipitate)
c) Equations to solve for the concentrations:
1) Dissociation of the triprotic acid H3PO4:
H3PO4 ⇌ H2PO4- + H+
H2PO4- ⇌ HPO42- + H+
HPO42- ⇌ PO43- + H+
2) Reaction between CaCl2 and phosphoric acid:
Ca2+ + 2Cl- + 2H2PO4- ⇌ CaHPO4 + 2HCl
3) Solubility equilibrium of CaHPO4:
CaHPO4 ⇌ Ca2+ + HPO42-
To solve for the concentrations of all the species in the system, we will express them in terms of x (concentration) and solve the set of equations using the given equilibrium constants and initial concentrations of phosphoric acid and CaCl2.
Remember, the concentrations of the species will change due to the reactions occurring. This means that once we've solved for the concentrations of all species, we can determine whether CaHPO4 will precipitate by comparing Qsp (which depends on the concentrations of Ca2+ and HPO42-) to Ksp.
I hope this helps! Let me know if you have any further questions.