A saturated solution contains the maximum amount of salt that can be dissolved in a given quantity of water at a specific temperature. For common table salt (sodium chloride, NaCl) in water, this exact amount is approximately 35.9 to 36.0 grams per 100 milliliters of water at standard room temperatures, visually confirmed when excess salt remains undissolved.
Understanding the Saturation Point
The concept of a saturated solution is fundamentally about a solvent's capacity to dissolve a solute. As highlighted in the provided video reference, you create a saturated solution by "continu[ing] adding salt until you find that some salt remains. Undissolved." This observation is the key indicator: once salt stops dissolving and simply settles at the bottom, the solution has reached its saturation point. At this stage, the water has dissolved the maximum possible amount of salt it can hold under those conditions.
The Exact Amount of Salt (Sodium Chloride)
The precise quantity of salt in a saturated solution primarily depends on the type of salt and the temperature of the water. For the most common salt, sodium chloride (NaCl), in water, the solubility is well-documented:
- At 20°C (68°F): Approximately 35.9 grams of NaCl can dissolve in 100 milliliters (mL) of water. Since 100 mL of water weighs approximately 100 grams, this is often stated as 35.9 grams per 100 grams of water.
- At 25°C (77°F): Slightly more, about 36.0 grams of NaCl, can dissolve in 100 mL (or 100 grams) of water.
This means that for every 100 mL of water, a saturated solution of common salt will contain roughly 35.9 to 36.0 grams of dissolved salt. Any additional salt beyond this amount will not dissolve and will remain as a solid, confirming the solution's saturation.
Factors Influencing Salt Solubility
While the values above are standard, a few factors can slightly alter the exact saturation point:
- Temperature: For most solids, including salt, solubility generally increases with increasing temperature. However, the solubility of NaCl shows only a slight increase with temperature.
- Type of Salt: Different salts have vastly different solubilities. For instance, potassium chloride (KCl) has a different saturation point than sodium chloride (NaCl). This answer focuses specifically on common table salt.
- Pressure: For solutions of solids in liquids, changes in pressure have a negligible effect on solubility.
Practical Application of Saturation
Consider preparing a large batch of a saturated salt solution. If you have 1 liter (1000 mL) of water at 20°C, you would need to dissolve approximately:
(35.9 grams NaCl / 100 mL water) × 1000 mL water = 359 grams of NaCl
Adding 360 grams of salt would result in 1 gram remaining undissolved, signaling that the solution is fully saturated.
| Temperature | Approximate Solubility of NaCl in Water |
|---|---|
| 20°C (68°F) | 35.9 grams per 100 mL (or 100 g) water |
| 25°C (77°F) | 36.0 grams per 100 mL (or 100 g) water |
In conclusion, a saturated salt solution contains the maximum amount of dissolved salt for specific conditions, a quantity that is precisely measurable and is visually identified when no more salt can dissolve, as demonstrated by the presence of undissolved solid salt.
