When the solution of calcium hydroxide, Ca(OH)₂, is heated, the following occurs:
- A. The amount of Ca(OH)₂ decreases: Yes, heating the solution provides energy that promotes the dissociation of calcium hydroxide into its constituent ions, Ca²⁺ and OH⁻ ions. Since calcium hydroxide is somewhat soluble in water, the increased temperature can enhance this solubility, leading to a greater concentration of these ions in solution.
- B. The amount of Ca²⁺ ions increases: As Ca(OH)₂ dissociates more readily upon heating, the concentration of free Ca²⁺ ions in the solution indeed increases. This is particularly important in applications where calcium ions are required, such as in construction and chemical processes.
- C. The concentration of hydroxide ions (OH⁻) increases: Along with the calcium ions, the hydroxide ions also increase as a result of the dissociation of calcium hydroxide. Heating the solution pushes the equilibrium towards the formation of more Ca²⁺ and 2OH⁻ ions.
In summary, heating a solution of calcium hydroxide leads to an increase in both Ca²⁺ and OH⁻ ions while the solid Ca(OH)₂ may decrease in amount due to its dissolution.