PSc.2.1 OBJECTIVE: Understand types, properties and structure of matter.
PSc.2.1 OBJECTIVE: Understand types, properties and structure of matter. Objectives PSc.2.1.1 – Classify matter as: homogeneous or heterogeneous; pure substance or mixture; element or compound; metals, nonmetals or metalloids; solution, colloid or suspension. SHOE CLASSIFICATION ACTIVITY 3 Matter Flowchart MATTER yes Can it be physically separated? MIXTURE yes Is the composition uniform? Homogeneous Mixture (solution) PURE SUBSTANCE no Heterogeneous Mixture Colloids no yes Can it be chemically decomposed? Compound Suspensions no Element Homogeneous vs Heterogeneous If matter is not uniform throughout, then it is a heterogeneous. If matter is uniform throughout, it is homogeneous. Homogeneous Matter Salt water, apple juice and dust free air (mixture of nitrogen, oxygen, argon, carbon dioxide, water vapor and other gases) are examples of homogeneous materials. Homogeneous Matter Brass (solid mixture of copper and zinc) is also homogeneous. Brass is an alloy, which is a mixture of metals. Heterogeneous Matter Oil-and-vinegar salad dressing, which has a layer of oil floating on a layer of vinegar, is heterogeneous. Homogeneous vs. Heterogenous Matter Classify the following substances and mixtures as either homogeneous or heterogeneous. Flat soda pop, cherry vanilla ice cream, salad dressing, sugar, soil, aluminum foil, black coffee, sugar water, city air, paint, alcohol, iron, beach sand, pure air, spaghetti sauce. 10 Homogeneous vs. Heterogeneous Matter Homogeneous Sugar Aluminum foil Black coffee Sugar water Iron Pure air Alcohol Flat soda pop Heterogenous Cherry vanilla ice cream Salad dressing Soil City air Paint Beach sand Spaghetti sauce 11 Pure Substances A pure substance always has the same composition. Pure substances are either elements or compounds. Elements Elements are substances that cannot be broken down into other substances chemically or physically. Examples include sodium, carbon and gold. Elements Elements – composed of identical atoms – Ex: copper wire, aluminum foil Compounds Compound – composed of 2 or more elements in a fixed ratio – properties differ from those of individual elements – Ex: table salt Compounds Another example of a compound includes water (hydrogen and oxygen). Mixtures A mixture can be defined as something that has variable composition. Soda is a mixture (carbon dioxide is dissolved in it), and coffee is a mixture (it can be strong, weak or bitter). Heterogeneous Mixtures A heterogeneous mixture contains regions that have different properties from those of other regions. When we pour sand into water, the resulting mixture contains two distinct regions. Homogeneous Mixtures Homogeneous mixtures (also known as solutions) are mixtures in which the composition is uniform, there are no chunks or layers. Substances vs. Mixtures Classify the following as to whether it is a substance or a mixture. Sodium, water, soil, coffee, oxygen, alcohol, carbon dioxide, cake batter, air, soup, iron, salt water, ice cream, nitrogen, eggs, blood, table salt, nail polish, milk, cola 20 Substances vs. Mixtures Substances Sodium (Na) Water (H2O) Oxygen (O2) Carbon Dioxide (CO2) Iron (Fe) Nitrogen (N2) Table Salt (NaCl) Mixtures Soil Coffee Cake batter Air Soup Salt water Ice cream Eggs Blood Nail polish Milk Cola Alcohol 21 Identification Activity Classify the contents of each bag as an element, compound, or mixture. Justify your answers. 22 Pure Substances and Mixtures Question Classify each of the following as a pure substance, a homogeneous mixture or a heterogeneous mixture. A. gasoline homogeneous mixture B. copper metal pure substance Question Classify each of the following as a pure substance, a homogeneous mixture or a heterogeneous mixture. C. a stream with gravel at the bottom heterogeneous mixture D. chunky peanut butter heterogeneous mixture Question Classify each of the following as a pure substance, a homogeneous mixture or a heterogeneous mixture. E. a multivitamin tablet homogeneous mixture F. carbon dioxide gas pure substance Quiz 1. 2. 3. 4. 5. _____ has mass and occupies space. Elements _____ be broken down into simpler substances. Pure substances include _____ and _____. The formula H2O formula represents a _____ of water. Mixtures are formed from _____ substances. 27 Tyndall Effect The Tyndall Effect is light scattering by particles in a colloid or particles in a fine suspension. Tyndall Effect The Tyndall Effect is shown on the left. Solution Colloid Suspension type particle size Tyndall Effect “Settle out” Example 29 Mixtures Solution – homogeneous – very small particles – no Tyndall effect – particles don’t settle – Ex: rubbing alcohol Mixtures Colloid – heterogeneous – medium-sized particles – Tyndall effect – particles don’t settle – Ex: milk Mixtures Suspension – heterogeneous – large particles – Tyndall effect – particles settle – Ex: freshsqueezed lemonade Question Classify each of the following as a solution, colloid or suspension. A) mayonnaise colloid B) muddy water suspension Question Classify each of the following as a solution, colloid or suspension. C) fog colloid D) salt water solution Question Classify each of the following as a solution, colloid or suspension. E) Italian salad dressing suspension Quiz 1. 2. 3. 4. A difference in what physical property is often used to separate two immiscible liquids? Fog and smoke are examples of what type of heterogeneous mixture? What is another term for a homogeneous mixture? What is an alloy? 36 Quiz 1. 2. 3. 4. The temperature at which a solid becomes a liquid. Ability of a substance to burn in the presence of oxygen. Ability of a substance to combine chemically with another substance. Mass per unit volume of a substance. a. b. c. d. e. Melting point Boiling point Density Reactivity Flammability 37
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