Solubility and the Dissolving Process
Chapter 7.2 and 7.3
What is solubility?
• The amount of solute that will dissolve into a solvent (at a certain pressure and temperature)
• Remember, solute is the smaller amount of a substance and the solvent is the larger portion of what is combined
Different substances have different solubilities…
• Solubilities of some ionic compounds in water
How to describe how much solute is dissolved in the solvent…
• Concentration—the amount of a particular substance in a solution – Large amount of solute = concentrated solution– Small amount of solute = dilute solution
How concentrated are solution?
• Saturated solution—a solution that cannot dissolve anymore solute into it (It’s full!)
• Unsaturated solution—a solution where more solute can still be dissolved into it (“contains less solute than the saturated solution”)
Temperature… • The solubility increases as the temperature of
the solution increases (if you heat up the solution, more can be dissolved into it!)
• Supersaturated solution—a solution that holds more dissolve solute than the regular equilibrium saturated state
How to make a crystal…• Heat up a solution, dissolve more solute in
than can normally dissolve, then cool back down the solution
• Add one extra bit of solute (a crystal of solute”) and the whole solution and extra solute will crystallize out!
What affects the dissolving process?
• Stirring or shaking (helps solute dissolve faster by bumping them against the solute particles faster)
• Heating up the solvent (particles move faster with more energy)
• Larger surface area increases dissolving rate (more area of the solute to interact with the solvent)
Solute affect the physical properties of solutions…
• Adding solute will cause…– The boiling point of a solution to increase (boiling
point elevation) – The freezing point of a solution to decrease
(freezing point depression)• So, instead of water freezing at 0 degrees Celsius, it
freezes at -15 degrees Celsius.
Your mission…• …if you choose to accept it….