Question

Indicate whether each statement is true or false: (a) The higher the temperature, the more soluble most gases are in water. (b) The higher the temperature, the more soluble most ionic solids are in water. (c) As you cool a saturated solution from high temperature to low temperature, solids start to crystallize out of solution if you achieve a supersaturated solution. (d) If you take a saturated solution and raise its temperature, you can (usually) add more solute and make the solution even more concentrated.

Short answer

(a) False - The solubility of gases in water generally decreases with an increase in temperature. (b) True - The solubility of most ionic solids in water usually increases with an increase in temperature. (c) True - When a saturated solution cools down and becomes supersaturated, solids start to crystallize out of the solution. (d) Generally True - When the temperature increases, more solute can be added to a saturated solution to make it even more concentrated, especially for ionic solids. However, for gases, this statement is false, as their solubility decreases with increasing temperature.

Step-by-step solution

Statement (a)

The statement says that the higher the temperature, the more soluble most gases are in water. This statement is incorrect, as the solubility of gases in water generally decreases with an increase in temperature. Thus, this statement is false.

Statement (b)

The statement says that the higher the temperature, the more soluble most ionic solids are in water. In general, this statement is correct. When the temperature increases, the solubility of most ionic solids in water usually increases. So, this statement is true.

Statement (c)

The statement refers to the process of cooling a saturated solution: as temperature decreases, solids start to crystallize out of the solution if it becomes supersaturated. This statement is true. When a saturated solution cools down, its solubility decreases; this creates a supersaturated condition, where there is more solute dissolved in the solution than its solubility allows at the new lower temperature. As a result, the excess solute starts to crystallize out of the solution.

Statement (d)

The statement says that if the temperature of a saturated solution is raised, more solute can be added to make the solution even more concentrated. This statement is generally true, especially for ionic solids. When the temperature increases, the solubility of most ionic solids in water also increases, which means that more solute can be added to the solution before reaching saturation. However, for gases this statement would be false, as the solubility of gases in water decreases with increasing temperature.

Key concepts

Temperature Effects on Solubility

Temperature plays a crucial role in determining the solubility of substances in water. For most solids, such as salts, as temperature increases, their solubility tends to increase as well. This means that you can dissolve more of the solid in a solvent at a higher temperature.

When it comes to gases, the situation is different. As the temperature of water rises, the solubility of gases decreases. This occurs because increased kinetic energy at higher temperatures allows gas molecules to escape from the liquid more easily.

Here's a quick summary of temperature effects on solubility:

• Increased temperature often increases solubility for solids.
• Increased temperature usually decreases solubility for gases.

Knowing these effects is important in various applications, like improving reaction rates in industrial processes or understanding environmental phenomena, such as decreased oxygen in warm water bodies.

Gas Solubility in Water

Gas solubility in water is inversely related to temperature. Gases are unique because as water heats up, their solubility decreases. This means fewer gas molecules can be held within the water at higher temperatures.

Think about a soda can: when opened, if it's warm, it fizzes more quickly than when cold. This fizzing is gas escaping from the liquid quickly because of lowered solubility at higher temperatures.

Several factors influence gas solubility in water:

• Temperature: Higher temperatures reduce solubility.
• Pressure: Increasing pressure can increase gas solubility.
• Nature of Gas: Different gases have varying solubility levels.

Understanding how gases dissolve in water is essential for studying aquatic environments, designing industrial processes, and even in simple everyday contexts such as carbonated drinks.

Ionic Solids Solubility

The solubility of ionic solids, like table salt and other similar compounds, generally increases with temperature. Ionic compounds dissolve in water due to the breaking apart of their positive and negative ions, which then get surrounded and stabilized by water molecules.

When the water temperature increases, its molecules move more vigorously, helping to break down the solid structure of ionic compounds more effectively. This allows more solute to dissolve, resulting in higher solubility.

Here's why ionic solid solubility matters:

• Increased solubility with temperature can help dissolve unwanted deposits from pipes in industrial applications.
• Allows for creating more concentrated solutions at higher temperatures for various chemical reactions.

Understanding the behavior of ionic solid solubility with temperature is essential for tasks varying from cooking to large-scale industrial processes.