* Ionic Compounds: Both NaCl and CaCl₂ are ionic compounds. They form crystal lattices with strong electrostatic interactions between their ions.
* Melting Point: The melting point is the temperature at which the solid state transitions to the liquid state. This happens when the thermal energy overcomes the electrostatic forces holding the ions together.
* Effect of CaCl₂: When CaCl₂ is added to NaCl, it disrupts the NaCl crystal lattice. However, the Ca²⁺ ions from CaCl₂ have a stronger electrostatic attraction to the Cl⁻ ions than the Na⁺ ions do. This creates a more tightly bound structure with a higher melting point.
In essence, the addition of CaCl₂ creates a mixed ionic compound with stronger electrostatic forces, leading to a higher melting point.
Important Note: While the addition of CaCl₂ raises the melting point of NaCl, the mixture will melt at a lower temperature than pure CaCl₂ because the CaCl₂ is diluted by the NaCl.
