The key difference between salt in water and sand in water lies in their interaction with the water: salt dissolves in water, forming a solution, while sand does not dissolve, remaining as a suspension.
Based on the provided information, we know that both salt and sand are non-magnetic solids. However, their behavior when mixed with water is fundamentally different due to their solubility properties.
- Salt (Sodium Chloride) is a soluble solid. When mixed with water, the salt particles break down and disperse evenly throughout the water, forming a homogeneous mixture called a salt solution. You cannot see the individual salt particles, and the mixture is clear (unless other impurities are present).
- Sand is an insoluble solid. When mixed with water, the sand particles do not dissolve. They remain as solid particles suspended in the water, forming a heterogeneous mixture. Over time, if left undisturbed, the sand particles will settle at the bottom due to gravity. The mixture often appears cloudy or murky.
Comparing Salt and Sand in Water
Here's a simple comparison based on their properties in water:
| Feature | Salt in Water | Sand in Water |
|---|---|---|
| Solubility | Soluble (dissolves) | Insoluble (does not dissolve) |
| Mixture Type | Solution (Homogeneous) | Suspension (Heterogeneous) |
| Appearance | Clear (assuming pure water/salt) | Cloudy/Murky, particles visible |
| Settling | Does not settle | Settles over time |
| Magnetic? | No (Non-magnetic solid) | No (Non-magnetic solid) |
Practical Application: Separating Sand and Salt
The difference in solubility is a practical way to separate a mixture of sand and salt. The easiest method, as mentioned in the reference, utilizes this property:
- Dissolve the salt: Add water to the mixture of sand and salt. Stir thoroughly. The salt will dissolve in the water, while the sand will not.
- Separate the sand: Carefully pour the liquid (the salt solution) away from the solid sand that has settled at the bottom. This can be done by decanting or filtering.
- Obtain the salt: The remaining liquid is salt water. Evaporate the water (e.g., by heating or leaving it in a warm place). As the water turns into vapor and disappears, the solid salt will be left behind.
This method highlights the fundamental difference: one substance integrates with the water at a molecular level (dissolves), while the other does not and can be physically separated.
