Cobalt(II) chloride, a blue solid, can absorb water from the air to form cobalt(II) chloride hexahydrate, a pink solid. The equilibrium is so sensitive to moisture in the air that CoCl₂ is used as a humidity indicator.Write a balanced equation for the equilibrium. Be sure to include water as a reactant to produce the hexahydrate.

Verified step by step guidance

1. Identify the chemical formula for cobalt(II) chloride, which is \( \text{CoCl}_2 \).
2. Recognize that cobalt(II) chloride hexahydrate is formed by absorbing water, and its chemical formula is \( \text{CoCl}_2 \cdot 6\text{H}_2\text{O} \).
3. Write the reactants for the equilibrium: \( \text{CoCl}_2 \) and water \( \text{H}_2\text{O} \).
4. Write the products for the equilibrium: \( \text{CoCl}_2 \cdot 6\text{H}_2\text{O} \).
5. Combine the reactants and products to form the balanced equation: \( \text{CoCl}_2 + 6\text{H}_2\text{O} \rightleftharpoons \text{CoCl}_2 \cdot 6\text{H}_2\text{O} \).

Key Concepts

Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. In the case of cobalt(II) chloride, the equilibrium between the anhydrous form and the hydrated form is influenced by external conditions, such as humidity. Understanding this concept is crucial for writing balanced equations that accurately represent the dynamic nature of the reaction.

Hydration and Hydrates

Hydration refers to the process where water molecules are incorporated into a compound, forming a hydrate. Cobalt(II) chloride hexahydrate (CoCl₂·6H₂O) is an example where six water molecules are associated with each cobalt(II) chloride unit. Recognizing how water interacts with ionic compounds is essential for understanding the formation of hydrates and their properties.

Balancing Chemical Equations

Balancing chemical equations involves ensuring that the number of atoms for each element is the same on both sides of the equation. This is important for obeying the law of conservation of mass. In the case of the cobalt(II) chloride equilibrium, one must account for the water molecules and the stoichiometry of the reactants and products to accurately represent the reaction.