Which of the following solutions is the most basic? a. 0.6𝑀 NH3 b. 0.150 M KOH c. 0.100𝑀Ba(OH)2

Verified step by step guidance

1. Identify the nature of each compound: NH3 is a weak base, KOH is a strong base, and Ba(OH)2 is a strong base.
2. For strong bases like KOH and Ba(OH)2, determine the concentration of hydroxide ions (OH⁻) they produce. KOH dissociates completely to give 0.150 M OH⁻, while Ba(OH)2 dissociates to give 0.200 M OH⁻ (since it produces two OH⁻ ions per formula unit).
3. For the weak base NH3, use the base dissociation constant (Kb) to estimate the concentration of OH⁻ ions it produces. This requires setting up an equilibrium expression and solving for OH⁻ concentration.
4. Compare the OH⁻ concentrations from each solution: higher OH⁻ concentration indicates a more basic solution.
5. Determine which solution has the highest OH⁻ concentration to identify the most basic solution.

Key Concepts

pH and Basicity

pH is a measure of the hydrogen ion concentration in a solution, indicating its acidity or basicity. A pH greater than 7 signifies a basic solution. Basicity refers to the ability of a substance to accept protons (H+) or donate electron pairs, with stronger bases resulting in higher pH values.

Concentration of Hydroxide Ions

The basicity of a solution is often determined by the concentration of hydroxide ions (OH-). Strong bases, such as KOH and Ba(OH)2, dissociate completely in water, increasing the OH- concentration. The more hydroxide ions present, the more basic the solution will be.

Dissociation of Bases

Different bases dissociate in water to varying extents. For example, KOH is a strong base that fully dissociates into K+ and OH-, while Ba(OH)2 also dissociates completely, producing two moles of OH- per mole of Ba(OH)2. NH3, on the other hand, is a weak base that does not fully dissociate, making its contribution to basicity less significant compared to strong bases.