Classification of Matter Matter Mixtures (Impure) (2 or more chemical entities) Objectives: Be able to 1. identify that a sample is a mixture 2. use physical observations to classify the different mixture types: solutions, suspensions or colloids Pure substances (one chemical entity) Mixtures 2 or more substances combined uniform (same) throughout non-uniform homogeneous mixtures heterogeneous mixtures colloids suspensions Mixtures 2 or more substances combined uniform (same) throughout non-uniform homogeneous mixtures solid liquid gas All solutions have a solute (lesser percentage) dissolved in a solvent (higher percentage) solid Alloys: uniform mixtures of a metal with other metals or elements Examples: Brass (copper and zinc) Bronze (copper and tin) Steel (iron, carbon and other metals) Hint!! If you know it is a metal, but it is not an element on the Periodic Table it must be …. liquid A liquid solution is some type of solute (solid, liquid or gas) dissolved in a liquid solvent All liquid solutions are clear, but they can be colored. If the solvent is water, the solution is called aqueous An aqueous solution can be represented by the phase subscript (aq) For example: NaCl(aq) means a solution of NaCl (sodium chloride) solute dissolved in water gas A gaseous solution has a gas as the solvent. Solutes can be liquids or gases. An example of a gaseous solution is your breath, which is a homogeneous mixture of air, carbon dioxide and water. Mixtures 2 or more substances combined non-uniform heterogeneous mixtures colloids suspensions The main difference between a colloid and a suspension is that a suspension will settle, or separate, over time. A colloid will appear uniform to the naked eye, though it is not uniform on a microscopic level. heterogeneous mixtures non-uniform colloids Colloids are generally recognized as either gels, foams or emulsions. A foam contains some type of gas (often air) dispersed throughout a liquid or solid. An emulsion is something creamy, like mayonnaise. Colloids will always exhibit the Tyndall effect (scattering of light) even if they appear to be clear to the naked eye. heterogeneous mixtures non-uniform suspensions A suspension contains easily visible parts, either layers or particles, which separate over time. If the label says “Shake before using”, that means it is a suspension. An example is medicine for babies. Questions: Answer the following questions in your notebook. Be sure to number your answers. This will be shown to your teacher for a homework grade. 1. What are the two main parts of a solution? 2. Other than the examples given in this PowerPoint. List two more examples of solid solutions. 3. Identify the solute and solvent in seltzer water. 4. Air is about 79% nitrogen, 20% oxygen and 1% other gases. What is the solvent in air? Explain your choice. 5. What is the main difference, in appearance, between a colloid and a suspension? 6. What type of mixture is the cream (the white filling) in an oreo cookie?