what do you observe when detergent is mixed with CaCl2
The correct answer and explanation is:
Correct Answer:
When detergent is mixed with calcium chloride (CaCl₂), a precipitate forms due to the reaction between calcium ions (Ca²⁺) and the anionic components of the detergent (often sulfonates or carboxylates), forming insoluble calcium salts.
Explanation (300 words):
Detergents are cleaning agents made of molecules called surfactants, which usually contain a hydrophobic tail (nonpolar) and a hydrophilic head (polar). The hydrophilic part is often anionic (negatively charged), such as a sulfonate (-SO₃⁻) or carboxylate (-COO⁻) group. These surfactants dissolve well in water and help remove dirt and grease by surrounding and emulsifying nonpolar substances.
When CaCl₂ (calcium chloride) is added to a solution containing detergent, Ca²⁺ ions (calcium ions) are released into the solution. Calcium ions are divalent cations, meaning they have a +2 charge and can interact strongly with the negatively charged heads of detergent molecules.
Many detergents form soluble salts with sodium (Na⁺), which is monovalent and does not cause precipitation. However, calcium ions can displace sodium from the detergent molecules and form insoluble calcium salts. This reaction results in a precipitate—a solid substance that separates from the solution. The precipitate is often a white, curdy substance, and it reduces the effectiveness of the detergent.
This phenomenon is especially relevant in hard water, which contains high concentrations of calcium and magnesium ions. The presence of these ions interferes with soap and detergent action, leading to soap scum or detergent residues that do not dissolve properly.
Summary of the observation:
- Formation of a white precipitate
- Reduction in foaming or cleaning ability
- Caused by the reaction between Ca²⁺ ions and the anionic detergent molecules
This is why water softeners or specially formulated detergents are used in hard water areas to prevent such precipitation and maintain cleaning efficiency.