Solutions

Remember mixtures? Mixture Heterogeneous Homogeneous A combination of two or more substances that are not chemically combined and can be separated by physical means. Two types: Mixture Heterogeneous Homogeneous

So, what does this have to do with solutions? A solution is a homogeneous mixture of two or more substances in a single phase. Thoroughly mixed Same Composition Throughout Same Properties Throughout

What makes up a solution? Solute: the substance being dissolved Solvent: the substance doing the dissolving Name the solute and solvent: solution solute(s) solvent Ocean water Coca-cola Humid air salt water Sugar, carbon dioxide water Water vapor air

Solute Solvent Gas Liquid Solid Examples of solutions Solvent Gas Liquid Solid Oxygen and other gases in nitrogen (air) Carbon dioxide in water (carbonated water) Hydrogen dissolves rather well in metals; platinum has been studied as a storage medium Water vapor in air (humidity) Ethanol (common alcohol) in water; various hydrocarbons in each other (petroleum) Water in activated charcoal; moisture in wood The odor of a solid results from molecules of that solid being dissolved in the air Sucrose (table sugar) in water; sodium chloride (table salt) in water Steel, brass, other metal alloys Solute Adapted from http://en.wikipedia.org/wiki/Solution

What types of solutions are there? Aqueous solutions (aq): solutions in which water is the solvent. Electrolytes: specific aqueous solutions in which the solute dissolves to form ions. Tinctures: solutions in which alcohol is the solvent. Alloys: solid solution of two or more metals. Amalgams: specific alloys in which one of the metals is mercury.

Suspensions Example: If the particles in a solvent are so large that they settle out unless the mixture is constantly stirred or agitated, the mixture is called a suspension. Suspensions Example: Muddy Water

Colloids Examples: Particles that are intermediate in size between those in solutions and suspensions form mixtures known as colloidal dispersions, or colloids. Colloids Examples: paints, mud, gelatin, milk, mayonnaise, shaving cream, smoke, fog, butter

Tyndall Effect A beam of light distinguishes a colloid from a solution. The particles in a colloid will scatter light, making the beam visible. NaCl Solution Gelatin and Water

Solutes: Electrolytes vs. Nonelectrolytes Electrolyte Dissolves in water to give a solution that conducts an electric current. Electrolyte Ionic Compounds (NaCl) Highly Polar Molecular Compounds (HCl)

Nonelectrolyte Dissolves in water to give a solution that does not conduct electrical current. Neutral solute molecules (not charged particles). Sugar is a nonelectrolyte.