Question

Why does NaCl have a high melting point but readily dissolves in water?

Answer 1

NaCl has a high melting point due to strong ionic bonds in the crystal lattice, requiring significant energy to break. It dissolves in water as the polar nature of water leads to dissociation of NaCl into its ions, facilitated by ion-dipole interactions.

Step-by-step explanation:

• Sodium chloride (NaCl) has a high melting point because its ionic crystal lattice structure is very strong due to the many simultaneous attractions between positively charged sodium ions (Na+) and negatively charged chloride ions (Cl-).
• These attractions, known as ionic bonds, require a significant amount of energy to be broken.
• Melting an ionic compound like NaCl involves overcoming all these bonds, explaining why a high melting temperature of about 800°C is required.

• On the other hand, when NaCl dissolves in water, it undergoes a process called dissociation where the distinct polar nature of water molecules allows them to interact strongly with the individual Na+ and Cl- ions.
• The partial positive charge of the hydrogen end and the partial negative charge of the oxygen end of the water molecules effectively surround and separate the ions, pulling them into solution.
• This ion-dipole interaction is crucial in dissolving ionic compounds in polar solvents like water, but not in non-polar solvents like hexane which lacks a dipole moment and thus cannot solvate the ions.

Answer 2

NaCl IS READILY SOLUBLE IN WATER DUE TO HIGH HYDRATION ENERGY

BUT HAVE HIGH MELTING POINT DUE TO STRONG ELECTROSTATIC FORCE BETWEEN SODIUM AND CHLORIDE IONS.

Step-by-step explanation:

Sodium has low melting point 98 deg celcius. In water sodium gets floated.

But sodium chloride have a high melting point because lattice is constructed due to strong electro-static force between positive sodium ions and negative chloride ions as they attract each other. This leads to strong construction so, NaCl have high temperature to break the bonds between the ions.

The melting temperature depends on the charge of the ions. Due to high hydration energy the sodium ions are readily soluble in water. Water can dissolve salt because the positive part of water molecules attracts negative chloride ions and negative part of water molecules attracts positive sodium ions.