1. Types of Mixtures, Rates of Solubility, and Molarity/Molality
Solutions
Types of Mixtures, Rates of Solubility, and Molarity/Molality

2. Types of Solutions Solutions Components of Solutions
Soluble – capable of being dissolved
Solution – homogeneous mixture of two or more substances in a single phase
Components of Solutions
Solvent – dissolving medium in a solution
Solute – substance dissolved in a solution

3. Types of Mixtures
May exist in all states of matter (gas, liquid, solid)
Examples:
Oxygen and Nitrogen gas (gas/gas)
Carbon Dioxide in water (gas/liquid)
Water in air (Liquid/gas)
Alcohol in water (Liquid/Liquid)
Mercury in Silver (Liquid/Solid)
Sugar in water (solid/liquid)
Copper in Nickel (Solid/Solid)

4. Types of Solutions
Suspensions – particles in a solvent are so large that they settle out unless the mixture is constantly stirred or agitated
Colloids – particles that are intermediate in size between those in solutions and suspensions form mixtures known as colloidal dispersions
Tyndall Effect
Particles are sometimes large enough to scatter light.
Light is scattered by colloidal particles dispersed in a transparent medium
Gelatin in water = colloid
Sugar and water = true solution

5. Tyndall Effect

6. Types of Solutions Solutes: Electrolytes v. Nonelectrolytes
Electrolyte – substance that dissolves in water to give a solution that conducts electric current
Nonelectrolyte – substances that dissolves in water to give a solution that does not conducts electric current

7. The Solution Process Factors Affect the Rate of Dissolution
Increasing the Surface Area of Solute
Agitating a Solution
Heating a Solvent

8. The Solution Process Solubility
Solution equilibrium – the physical state in which the opposing processes of dissolution and crystallization of a solute occur at equal rates.
Saturated v Unsaturated
Saturated - solution that contains the maximum amount of a dissolved solute
Unsaturated – solution that contains less solute than a saturated solution under the existing conditions

9. The Solution Process Supersaturated
A solution that contains more dissolved solute than a saturated solution contains under the same conditions
Solubility Values
The solubility of a substance is the amount of that substance required to form a saturated solution with specific amount of solvent at a specified temperature

10. The Solution Process Solute – Solvent Interactions
Dissolving Ionic Compounds in Aqueous Solution
Hydration – solution process with water as the solvent is referred
When crystallized from aqueous solutions, some ionic substances form crystals that incorporate water molecules.

11. The Solution Process Nonpolar Solvents
Ionic compounds are generally not soluble in nonpolar solvents such as carbon tetrachloride.
Non polar solvent molecules do not attract the ions of the crystal strongly enough to overcome the forces holding them together.

12. The Solution Process Liquid Solutes and Solvents
Immiscible – liquid solutes and solvents that are not soluble in each other
Miscible – liquids that dissolve freely in one another in any proportion

13. The Solution Process Effects of Pressure on Solubility
Increases in pressure increase gas solubilities in liquids
Henry’s Law – the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid.
There are no gas bubbles in an unopened bottle of soda because the pressure of CO2 applied during the bottling process keeps the carbon dioxide gas dissolved in the liquid.
Effervescence – rapid escape of a gas from a liquid in which it is dissolved

14. The Solution Process Effects of Temperature on Solubility
Increasing the temperature usually decreases gas solubility
The effect of temperature on the solubility of solids in liquids is more difficult to predict.
Often increasing the temperature increases the solubility of solids
However, an equivalent temperature increase can result in a large increase in solubility in one case and only a slight increase in another.

15. The Solution Process Heats of Solution
The net amount of heat energy absorbed or released when a specific amount of solute dissolves

16. Concentration of Solutions
Concentration – a measure of the amount of solute in a given amount of solvent or solution

17. Concentration of Solutions
Molarity
The number of moles of solute in one liter of solution
Molarity (M) =
Example: You have 3.50 L of solution that containes 90.0 g of sodium chloride. What is the molarity of that solution?
Given: solute mass = 90.0n g NaCl solution volume = 3.50 L
90.0 g NaCl x = 1.54 mol NaCl
= M NaCl

18. Concentration of Solutions
Now You Try
You have 0.8 L if 0.5 M HCl solution. How many moles of HCl does this solution contain?
To produce 40.0 g of silver chromate, you will need at least 23.4 g of potassium chromate in solution as a reactant. All you have on hand in the stock room is 5 L of a 6.0 M K2CrO4 solution. What volume of the solution is needed to give you the g K2CrO4 needed for the reaction?

19. Concentration of Solutions
What is the molarity of a solution composed of g of potassium iodide, KI, dissolved in enough water to make L of solution?
How many moles of H2SO4 are present in L ov a M H2SO4 solution?
What volume of 3.00 M NaCl is needed for a reaction that requires g of NaCl?

20. Concentration of Solutions
Molality
The concentration of a solution expressed in moles of solute per kilogram of solvent
Molality =

21. Concentration of Solutions
Example: A solution was prepared by dissolving 17.1 g of sucrose ( C12H22O11) in 125 g of water. Find the molal concentration of this solution.
Given: solute mass = 17.1 g sucrose
Solvent mass = 125 g water
17.1 g C12H22O11 x = mol C12H22O11
= m C12H22O11

22. Concentration of Solutions
Now You Try!
A solution of iodine, I2, in carbon tetrachloride is used when iodine is needed for certain chemical tests. How much iodine must be added to prepare a m solution of iodine in carbon tetrachloride if g of CCl4 is used?
What is the molality of a solution composed of 255 g of acetone, (CH3)2CO, dissolved in 200 g of water?
What quantity in grams of methanol, CH3OH, is required to prepare a m solution in 400 g of water?