Table of contents

1. Intro to General Chemistry3h 48m
2. Atoms & Elements4h 16m
3. Chemical Reactions4h 10m
4. BONUS: Lab Techniques and Procedures1h 38m
5. BONUS: Mathematical Operations and Functions48m
6. Chemical Quantities & Aqueous Reactions3h 53m
7. Gases3h 49m
8. Thermochemistry2h 37m
9. Quantum Mechanics2h 58m
10. Periodic Properties of the Elements3h 9m
11. Bonding & Molecular Structure3h 29m
12. Molecular Shapes & Valence Bond Theory1h 57m
13. Liquids, Solids & Intermolecular Forces2h 23m
14. Solutions3h 1m
15. Chemical Kinetics2h 53m
16. Chemical Equilibrium2h 29m
17. Acid and Base Equilibrium5h 1m
18. Aqueous Equilibrium4h 47m
19. Chemical Thermodynamics1h 50m
20. Electrochemistry2h 42m
21. Nuclear Chemistry2h 36m
22. Organic Chemistry5h 7m
23. Chemistry of the Nonmetals2h 39m
24. Transition Metals and Coordination Compounds3h 16m

6. Chemical Quantities & Aqueous Reactions

Solubility Rules

General Chemistry

6. Chemical Quantities & Aqueous Reactions

Solubility Rules

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Multiple Choice

Why does the addition of acid increase the solubility of calcium phosphate (Ca3(PO4)2) in water?

Acid causes the precipitation of calcium ions, removing them from solution and increasing solubility.

Acid reacts with phosphate ions to form H3PO4, reducing the concentration of PO4^{3-} and shifting the dissolution equilibrium toward more dissolved Ca3(PO4)2.

Acid increases the temperature of the solution, which directly increases the solubility of Ca3(PO4)2.

Acid neutralizes calcium ions, forming CaCl2 and increasing the solubility of Ca3(PO4)2.

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Verified step by step guidance

Identify the dissolution equilibrium of calcium phosphate in water: $\mathrm{Ca_3(PO_4)_2 (s) \rightleftharpoons 3 Ca^{2+} (aq) + 2 PO_4^{3-} (aq)}$.

Understand that the solubility depends on the concentrations of $\mathrm{Ca^{2+}}$ and $\mathrm{PO_4^{3-}}$ ions in solution, governed by the solubility product constant $K_{sp}$.

Recognize that adding acid introduces $\mathrm{H^+}$ ions, which react with phosphate ions to form various protonated phosphate species such as $\mathrm{HPO_4^{2-}}$, $\mathrm{H_2PO_4^-}$, and ultimately $\mathrm{H_3PO_4}$.

This reaction reduces the free $\mathrm{PO_4^{3-}}$ ion concentration in solution, disturbing the dissolution equilibrium and causing more $\mathrm{Ca_3(PO_4)_2}$ solid to dissolve to restore equilibrium according to Le Châtelier's principle.

Conclude that the increased solubility is due to the acid removing $\mathrm{PO_4^{3-}}$ ions from solution by protonation, shifting the equilibrium toward dissolution, rather than precipitation or temperature effects.