Presentation on theme: "II III I Lesson 1: The Nature of Solutions Unit 8 Solution Chemistry."— Presentation transcript:
II III I Lesson 1: The Nature of Solutions Unit 8 Solution Chemistry
Solution - Solution - homogeneous mixture of 2 or more substances in a single physical state
Characteristics of Solutions Particles (atoms, ions, molecules) are very small. Particles do not scatter light Liquid solutions are clear Cannot be easily separated by simple physical means. All parts of the solution are uniform or identical
Characteristics of Solutions A solution has 2 parts Solvent Solvent - present in greater amount Solute Solute - substance being dissolved
Solvation Solvation – Solvation – the process of dissolving It is the interaction between solute and solvent particles Energy is either required or released
Solvation A substance that dissolves in a solvent is said to be soluble. A substance that does not dissolve in a solvent is said to be insoluble. For liquid solute-solvent combinations: 2 liquids that are soluble are miscible 2 liquids that are not soluble are immiscible
Solvation solute particles are separated and pulled into solution solute particles are surrounded by solvent particles
Combinations of solute and solvents. SoluteSolventExample solid liquidsolid Solidliquid gasliquid gas
Solubility Solubility – the ability of one substance to dissolve in another maximum grams of solute that will dissolve in 100 g of solvent at a given temperature
Solubility SATURATED SOLUTION no more solute dissolves UNSATURATED SOLUTION more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form concentration
Solubility Solubility Curve shows the dependence of solubility on temperature
Factors Affecting Solubility NONPOLAR POLAR “Like Dissolves Like” 1. Nature of Solute and Solvent
Factors Affecting Solubility 2. Temperature Solids are more soluble at... high temperatures Gases are more soluble at... low temperatures
Factors Affecting Solubility 3. Pressure Gases are more soluble at... high pressures (Henry’s Law). EX: nitrogen narcosis, the “bends,” soda
Factors Affecting Solubility 3. Pressure Henry’s Law – At a given temperature, the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquid. S 1 = S 2 P 1 P 2
Henry’s Law Problem If 0.85 g of a gas at 4.0 atm of pressure dissolves in 1.0L of water at 25°C, how much will dissolve in 1.0L of water at 1.0 atm of pressure and the same temperature? S 1 = S 2 P 1 P 2
II III I Factors Affecting the Rate of Dissolving (solvation)
Factors Affecting Rate of Dissolving 1. Surface Area Increasing surface area increases dissolving. When the area of exposed surface is increased, more solute particles are subjected to solvation.
Factors Affecting Rate of Dissolving 2. Stirring Stirring increases dissolving. Without stirring, the solvent in contact with the solute becomes saturated thereby decreasing dissolving.
Factors Affecting Rate of Dissolving 3. Temperature Increasing the temperature of solvent increases dissolving. Increasing temperature, increases movement of solvent particles, more solute particles are subjected to solvation.