Question

The solubility of \(\mathrm{KNO}_{3}\) increases as the temperature rises. If a saturated solution of \(\mathrm{KNO}_{3}\) is heated to a higher temperature, will it still be a saturated solution? Explain.

Short answer

No, a saturated solution of \(\mathrm{KNO}_{3}\) when heated to a higher temperature will not remain saturated. This is because solubility of \(\mathrm{KNO}_{3}\) increases with temperature increase. So, it will become an unsaturated solution.

Step-by-step solution

Understand the Solubility Concept

Solubility is the ability of a substance to dissolve in another substance. In this case, we are dealing with \(\mathrm{KNO}_{3}\) dissolving in water. A solution is said to be saturated when it has dissolved all the \(\mathrm{KNO}_{3}\) it can at a given temperature. This implies that no more \(\mathrm{KNO}_{3}\) can be dissolved, any additional \(\mathrm{KNO}_{3}\) will simply settle at the bottom.

Evaluate the Influence of Temperature

Temperature plays a key role in solubility. For most solid substances like \(\mathrm{KNO}_{3}\), their solubility increases as the temperature of the solvent (water) increases. This means that at higher temperatures more \(\mathrm{KNO}_{3}\) can be dissolved in the same amount of water.

Apply the Concepts to the Question

If we heat a saturated \(\mathrm{KNO}_{3}\) solution to a higher temperature, it will no longer remain saturated. This is because the solubility of \(\mathrm{KNO}_{3}\) increases with temperature rise, meaning now it can dissolve more \(\mathrm{KNO}_{3}\). Therefore, the solution after heating can still dissolve more \(\mathrm{KNO}_{3}\), making it an unsaturated solution.

Key concepts

Solubility of Substances

The concept of solubility is fundamental to understanding how substances interact with solvents. Solubility refers to the maximum amount of a solute that can be dissolved in a solvent at a specific temperature and pressure, forming a homogeneous solution. In simpler terms, it is a measure of how well a substance, like salt or sugar, can dissolve in a liquid, such as water.

There are several factors that can affect solubility, including the nature of the solute and solvent, temperature, pressure, and the presence of other chemicals. For example, gases are generally more soluble in cold liquids, while solubility for most solid solutes increases with temperature. It's also interesting to consider that not all substances have the same solubility. Some substances, like ethanol in water, are miscible in all proportions, meaning they can mix in any amount without forming two separate layers.

Saturated Solution

Understanding what a saturated solution is can help us grasp how substances dissolve and react with each other. A saturated solution is one that contains the maximum amount of solute that can dissolve in a solvent at a specific temperature and pressure. Once that point is reached, no additional solute will dissolve; rather, it will begin to accumulate as a precipitate if you try to add more.

In the context of our example with potassium nitrate ((KNO3), if you've made a solution that's saturated, you've added as much of the (KNO3) as you can for that given amount of water and temperature. Any additional (KNO3) will only settle at the bottom of the container. It's also useful to know that a saturated solution can become unsaturated again if the temperature is raised, since this can increase the solubility of the solute.

Influence of Temperature on Solubility

Temperature is a vital factor in the solubility of substances. Generally, for many solid solutes, increasing the temperature of the solvent leads to an increase in solubility. This means that at higher temperatures, more of the solid solute can be dissolved in the solvent. The reasoning behind this is rooted in thermodynamics; higher temperatures increase the kinetic energy of the molecules involved, making it easier for the solute particles to disperse within the solvent.

However, this rule is not universal. For some substances, particularly gases, solubility decreases with an increase in temperature. When faced with a problem such as the solubility of (KNO3), remembering that this particular solute becomes more soluble with rising temperatures can lead to the realization that what was once a saturated solution at a lower temperature might not remain saturated after heating. It opens up capacity for more (KNO3) to be dissolved, thus the solution becomes unsaturated.