Melting point of NaCl decrease by CaCl2?

The melting point of NaCl actually increases with the addition of CaCl2. This is because CaCl2 is a stronger ionic compound than NaCl, meaning that the electrostatic forces between the ions are stronger. This results in a higher melting point for the mixture.

The melting point of a compound is the temperature at which it changes from a solid to a liquid. The melting point is determined by the strength of the intermolecular forces between the molecules or ions in the compound. The stronger the intermolecular forces, the higher the melting point.

In the case of NaCl and CaCl2, the intermolecular forces are ionic bonds. Ionic bonds are formed between positively and negatively charged ions. The strength of an ionic bond is determined by the charges on the ions and the distance between the ions. The greater the charges on the ions and the shorter the distance between the ions, the stronger the ionic bond.

CaCl2 has a higher charge than NaCl. This is because Ca2+ has a +2 charge, while Na+ has a +1 charge. The higher charge on Ca2+ results in a stronger ionic bond between Ca2+ and Cl- ions. This stronger ionic bond results in a higher melting point for CaCl2.

When CaCl2 is added to NaCl, the Ca2+ ions and Cl- ions from the CaCl2 disrupt the ionic bonds between the Na+ and Cl- ions in the NaCl. This disruption of the ionic bonds weakens the intermolecular forces between the ions in the mixture, resulting in a lower melting point for the mixture.

Therefore, the melting point of NaCl decreases with the addition of CaCl2.