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

Previous problemNext problem

Struggling with General Chemistry?

Join thousands of students who trust us to help them ace their exams!Watch the first video

Multiple Choice

According to general solubility rules, what is the solubility of Mg(OH)2 in pure water?

Mg(OH)2 is highly soluble in pure water.

Mg(OH)2 is moderately soluble in pure water.

Mg(OH)2 is mostly insoluble in pure water.

Mg(OH)2 is completely soluble in pure water.

Previous problemNext problem

Verified step by step guidance

Recall the general solubility rules for hydroxides: most hydroxides (OH⁻ compounds) are insoluble in water, except those of alkali metals (Group 1) and some alkaline earth metals like Ca(OH)₂, Sr(OH)₂, and Ba(OH)₂, which are moderately soluble.

Identify that magnesium hydroxide, Mg(OH)₂, is a hydroxide of an alkaline earth metal (magnesium is in Group 2), but unlike Ca(OH)₂, it has limited solubility in water.

Understand that 'mostly insoluble' means that only a small amount of Mg(OH)₂ dissolves in pure water, establishing an equilibrium between solid Mg(OH)₂ and its ions in solution.

Write the dissolution equilibrium for Mg(OH)₂: $\mathrm{Mg(OH)_2 (s) \rightleftharpoons Mg^{2+} (aq) + 2 OH^- (aq)}$ and recognize that the solubility product constant, $K_{sp}$, quantifies its solubility.

Conclude that based on the solubility rules and the low $K_{sp}$ value for Mg(OH)₂, it is mostly insoluble in pure water, meaning only a small concentration of Mg²⁺ and OH⁻ ions are present in solution.