Chapter 15: Classification of Matter - Study Guide

1 Name:_____Pd:_____Date:_____ Chapter 15: Classification of Matter - Study Guide Important Vocabulary: 1. Substance 2. Element 3. Compound 4. Heterogeneous Mixture 5. Homogeneous Mixture 6. Solution 7. Colloid 8. Tyndall Effect 9. Suspension 10. Physical Property 11. Physical Change 12. Distillation 13. Chemical Property 14. Chemical Change 15. Law of Conservation of Mass Important Concepts: Define substances and mixtures. Identify elements and compounds. Compare and contrast solutions, colloids, and suspensions. Identify substances using physical properties. Compare and contrast physical and chemical changes. Identify chemical changes. Define the law of conservation of mass. Practice Problems: 1. Explain the difference between a chemical and a physical property. 2. List two examples of chemical and physical properties. 3. Salt (NaCl) mixes with boiling water and completely dissolves. a. Which type of mixture is this? b. What would the salt and water each be called in this type of mixture?

2 C. What type of change is the salt undergoing? A physical property is a characteristic that can be observed without changing the chemical makeup of the substance. A chemical property can only be observed by changing the chemical structure of the substance. Chemical Property: flammability, ability to react with oxygen, if it reacts with an acid, Physical Property: color, weight, mass, boiling point, Homogeneous mixture - solution Water = the solvent Salt = the solute It is dissolving, which is a physical change 4. What type of mixture is fog? List a few properties of this type of mixture. 5. The air that we breathe is a homogeneous mixture. Explain why this is true. 6. List the two main types of pure substances. 7. What is the difference between an element and a compound? 8. What happens to the chemical identity of a substance if it undergoes a physical change? What happens in a chemical change? 9. Describe the difference between heterogeneous and homogeneous mixtures.

3 10. If you use the distillation process to separate salt from salt water, describe how this would happen. Is it a chemical or physical change? 11. Classify the following as elements, compounds, or mixtures: a. Aluminum - element b. Sulfur - element c. Carbon Dioxide - compound d. Water - compound e. Air - mixture f. Hydrogen - element Fog is a colloid. Colloids are homogeneous mixtures that have larger particles that do not settle out of the solution. When light is shined through a colloid, it scatters off of the particles. Air is a mixture of several different gases, such as oxygen, nitrogen, and carbon dioxide. It is considered homogeneous because the mixture looks the same throughout. Elements and Compounds An element is composed of identical atoms and cannot be broken down into simpler parts that share those same properties. A compound is composed of two or more elements that are combined in fixed proportions. In a physical change, the chemical identity stays the same!

4 In a chemical change, the chemical identity changes! A heterogeneous mixture is composed of two or more substances that are easily distinguishable from one another. A homogeneous mixture is composes of two or more substances that look identical throughout the mixture. Distillation is a process in which a mixture of two or more liquids is separated by heating the mixture to the boiling point of one of the substances. That substance will turn into a gas, separate itself from the liquid, condense back into a liquid, and then be collected in a separate container. This is a physical change! All separation techniques are considered physical changes!