Supersaturated Solutions Lab # 1 Name True solutions are ...
SOLUBILITY Objectives: * Understand the difference between Unsaturated, Saturated, and...
-
Upload
martha-wade -
Category
Documents
-
view
317 -
download
5
Transcript of SOLUBILITY Objectives: * Understand the difference between Unsaturated, Saturated, and...
SOLUBILITYObjectives:* Understand the difference between
Unsaturated, Saturated, and Supersaturated.
* Understand how to read Solubility Curves.
* Understand how to solve Percent Concentration Problems.
Solubility curve
Saturated
Unsaturated
Supersaturated
Solubility curve
• Any point on a line represents a saturated solution.
• In a saturated solution, the solvent contains the maximum amount of solute.
• Example: At 90oC, 40 g of NaCl in 100g H2O represent a saturated 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 in 100g H2O represent an unsaturated solution.
10 g of NaCl will have to be added to make the solution saturated.
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 very unstable and the amount in excess can precipitate or crystallize.
• Example: At 90oC, 50 g of NaCl in 100g H2O represent a supersaturated solution.
Solubility curve
Any solution can be made saturated, unsaturated, or supersaturated by changing the temperature.
In a few instances (e.g., Li2SO4 below) the solubility of the salt will decrease with temperature. This observation does not invalidate the above explanantion but rather suggests that several competing ideas need to be taken into account to fully understand chemical processes.
Solubility of Gases vs. Temperature• The variation of solubility for a gas with temperature
can be determined by examining the graph below:
• As the temperature increases, the solubility of a gas decreases as shown by the downward trend in the graph .
Units of Concentrations
The grams of solute per grams of solution equals the Percent Concentration.
= Percent Concentrationsolute
solution x 100
How do I get sugar to dissolve faster in my iced tea?
Stir, and stir, and stir
Add sugar to warm tea then add ice
Grind the sugar to a powder
Nature of the solute and solvent “Likes dissolve likes”
When two similar liquids - here water and methanol- are mixed, the molecules are intermingled. The mixture has a more disorderly arrangement of molecules than the separate liquids. It is this disordering process that largely drives solution formation.
• polar solute/polar solvent: EX: ethanol, salt, sugar in water
• nonpolar solute/nonpolar solvent: EX: Iodine in carbontetrachloride, gasoline or benzene
Electrolyte and Non-electrolyte
• Electrolyte: a substance that conducts electricity when dissolved in water. – Acids, bases and soluble ionic
solutions are electrolytes.
• Non-electrolyte: a substance that does not conduct electricity when dissolved in water. – Molecular compounds and insoluble
ionic compounds are non-electrolytes.
Electrolytes
• Allows an electric charge to be carried.
Types of solutes
Na+
Cl-
Electrolyte
Conducts electricity
Types of solutes
sugar
Nonelectrolyte
Does not conduct electricity