Solubility and Solubility Curves

Not All Things Dissolve the Same… When a solid dissolves into a liquid, the particles of solid break down into their individual parts and spread out throughout the liquid. BUT… this process isn’t the same for everything. We’re going to replace the word “Dissolve” with terms that are more specific to what is going on. It’s like when we converted to “Particle Palace”. We didn’t call them all particles, we were more specific and called them formula units, molecules, or atoms.

Not All Things Dissolve the Same… Ionic compounds will disassociate into their separate ions (think back to net ionic equations) Ex: Ca(OH)2 (s)  Ca2+(aq) + 2 OH-(aq)

Covalent Compounds Covalent compounds will still dissolve, but each molecule stays completely together, just spread further apart This is called dispersion Sugar is an excellent example of this C6H12O6 (s)  C6H12O6 (aq)

Acids – The in-between ones Acids are a bit special because they are covalent compounds, but they break into ions when mixed with water. So they get a special term… Ionization! Ex: HCl (g)  H+ (aq) + Cl- (aq)

What are Solutions Made Of? A solution is a homogeneous mixture of 2 or more substances in a single phase. The substance being dissolved (or is less concentrated) is the SOLUTE. The substance doing the dissolving (or is more concentrated) is the SOLVENT.

Solutions are not just solids dissolved in liquids! Solute Solvent Example solid Metal alloys 14-K Gold liquid Kool-Aid (Sugar in H2O) Wine or Vinegar Alcohol or Acid in H2O gas Carbonate Beverages (CO2 in H2O) Air (O2 and other gases in N2)

The amount of solute that dissolves in a specific amount of solvent. Solubility is The amount of solute that dissolves in a specific amount of solvent. Expressed as grams of solute in 100 grams ( or ml) of solvent water. Grams of solute 100 g/ml water

Unsaturated Types of Solutions Contain less than the maximum amount of solute. Can dissolve more solute. Dissolved solute

Saturated Types of Solutions Contain the maximum amount of solute that can dissolve. Has undissolved solute at the bottom of the container.

Supersaturated Types of Solutions An unstable solution that contains an amount of solute greater than normal.

Learning Check At 40C, the solubility of KBr is 80 g/100 g H2O. Identify the following solutions as either 1) Saturated, (2) Unsaturated, or (3) Supersaturated A. 60 g KBr added to 100 g of water at 40C. B. 120 g KBr added to 200 g of water at 40C. C. 75 g KBr added to 50 g of water at 40C.

These are stable and hard to decompose. Saturated fats are called saturated because all of the bonds between the carbon atoms in a fat are single bonds. These are stable and hard to decompose. Thus, these should be avoided in diets. Butter and oil are mostly saturated fats. Unsaturated fats have at least one double bond between carbon atoms. Thus, there are some bonds that can be brokenand used for a variety of purposes. These are REQUIRED to carry out many functions in the body. Game animals (chicken, deer) are usually less saturated, Olive and canola oil are examples as well.

Electrolytes in the Body Electrolytes are solutions that conduct electricity. Carry messages to and from the brain as electrical signals. Important to maintain cellular function with the correct concentrations electrolytes.

Solubility Curve Saturated Supersaturated Unsaturated

Solubility Curve Example At 90oC, 40 g of NaCl(s) in 100g H2O(l) represent a saturated solution. Any point on a line represents a Saturated Solution. In a saturated solution, the solvent contains the maximum amount of solute.

Any point below a line represents an Unsaturated Solution. Solubility Curve Any point below a line represents an Unsaturated Solution. In an unsaturated solution, the solvent contains less than the maximum amount of solute. Example At 90oC, 30 g of NaCl(s) in 100g H2O(l) represent an unsaturated solution. How much is required to saturate the solution?

Solubility Curve Any point above a line represents a Supersaturated Solution. In a supersaturated solution, the solvent contains more than the maximum amount of solute. A supersaturated solution is unstable and the excess amount can precipitate or crystallize. Example At 90oC, 50 g of NaCl(s) in 100g H2O(l). How much will NaCl(s) will precipitate?

Solubility Curve Any solution can be made saturated, unsaturated, or supersaturated by changing the temperature.