Ca2+(aq) + 2OH-(aq) → Ca(OH)2(s)
This reaction reveals the following:
1. Formation of Calcium Hydroxide Precipitate: The reaction results in the formation of a solid product, calcium hydroxide (Ca(OH)2). This substance is a white, powdery compound that is commonly known as slaked lime. It is sparingly soluble in water, which means that only a small amount of it dissolves, leading to the formation of a precipitate.
2. Chemical Combination: The reaction involves the chemical combination of calcium ions (Ca2+) and hydroxide ions (OH-) to form calcium hydroxide (Ca(OH)2). This process illustrates the basic principle of chemical reactions, where different substances interact and combine to form new products.
3. Precipitation Reaction: This reaction is an example of a precipitation reaction, which occurs when two solutions containing soluble ionic compounds react to form an insoluble product that precipitates out of the solution. In this case, calcium hydroxide has low solubility, so it precipitates as a solid.
4. Heat Release: This reaction is exothermic, meaning that it releases heat energy. The enthalpy change (ΔH) for this reaction is negative (-16.71 kJ), indicating that heat is released during the formation of calcium hydroxide.
5. Stoichiometry: The balanced chemical equation provides information about the stoichiometry of the reaction. For every one calcium ion (Ca2+), two hydroxide ions (OH-) are required to form one molecule of calcium hydroxide (Ca(OH)2). This quantitative relationship is important for determining the amounts of reactants needed and predicting the amount of product formed.
6. Aqueous Solution: The reaction takes place in an aqueous solution, where the reactants and products are dissolved in water.
Overall, this reaction demonstrates the formation of calcium hydroxide through the chemical combination of calcium and hydroxide ions, resulting in a precipitation reaction and release of heat energy.
