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Ch.16 - Acid-Base Equilibria
Chapter 16, Problem 46

Determine whether each of the following is true or false: (a) All strong bases are salts of the hydroxide ion. (b) The addition of a strong base to water produces a solution of pH > 7.0. (c) Because Mg(OH)2 is not very soluble, it cannot be a strong base.

Verified step by step guidance
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Step 1: Understand the definition of a strong base. A strong base is a compound that completely dissociates into its ions in water. Common strong bases include hydroxides of alkali metals and some alkaline earth metals.
Step 2: Analyze statement (a). Strong bases are typically metal hydroxides that dissociate completely in water, forming hydroxide ions (OH^-). Consider whether all strong bases fit this description.
Step 3: Evaluate statement (b). Recall that the pH scale measures the acidity or basicity of a solution, with pH > 7 indicating a basic solution. Consider the effect of adding a strong base to water on the pH.
Step 4: Examine statement (c). Consider the solubility of Mg(OH)_2 and its dissociation in water. A strong base dissociates completely, but solubility affects the concentration of ions in solution.
Step 5: Summarize your findings for each statement, determining whether each is true or false based on the definitions and properties of strong bases.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Strong Bases

Strong bases are substances that completely dissociate in water to produce hydroxide ions (OH-). Common examples include sodium hydroxide (NaOH) and potassium hydroxide (KOH). While many strong bases are hydroxides, not all strong bases are exclusively defined as salts of the hydroxide ion, as some can be derived from other compounds.
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pH Scale

The pH scale measures the acidity or basicity of a solution, with values ranging from 0 to 14. A pH of 7 is neutral, while values above 7 indicate basic solutions. The addition of a strong base to water typically results in a solution with a pH greater than 7, reflecting the increased concentration of hydroxide ions.
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Solubility and Strong Bases

Solubility refers to the ability of a substance to dissolve in a solvent, such as water. While strong bases are characterized by their complete dissociation in solution, some compounds, like magnesium hydroxide (Mg(OH)2), are not very soluble. This does not disqualify them from being classified as strong bases; rather, it indicates that their strength is not solely dependent on solubility.
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