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Unit 2 - Classifying Matter Time Frame Competencies C1. C2. C3. 2 weeks Demonstrate skill in identifying chemical systems and classification of matter. Appreciate understanding of elements and compounds present in daily life. Demonstrate simple techniques in the preparation, separation, and purification of mixtures. IDENTIFICATION OF CHEMICAL SYSTEMS Time Frame: 3 sessions I. Learning Objectives At the end of the session, the students must be able to: 1. Describe a pure substance and a mixture; 2. Observe and record data; 3. Make operational definitions of chemical systems, pure substances, and mixtures; 4. Recognize such chemical systems around them. II. Subject Matter A. Topic: Classification of chemical systems; purity of substances B. References 1. Department of Education, Culture and Sports. (1991). Science and Technology III. Quezon City: Book Media Press, pp. 29-40. 2. Brown, Theodore L., LeMay, H. Eugene Jr., and Bursten, Bruce E., (2000). Chemistry the Central Science. New Jersey: Prentice Hall, pp. 5-11. 3. Hill John W., and Kolb, Doris K.(1995). Chemistry for Changing Times, 7th Edition. London: Prentice Hall International, pp. 17-20. 4. Franco, Aurora A., et. al. Interactive Chemistry. pp. 28 - 29. C. Materials Water Vinegar Cooking Oil Sugar Salt Soy sauce Calamansi juice Shampoo Syrup Buttons, cork, coin, etc. 22 BSE-Department of Education III. Learning Tasks A. Recall and Motivation 1. Ask the students to write on a piece of paper the first word that comes to mind when they hear the word "matter". The words are then posted on the board. The following terms are written on colored cartolina: elements, compounds, colloids, substances, solutions, mixture, paper, food, carbon, oxygen, and air. 2. “Density Column Demonstration” Set-up: Note the layering of the liquids (oil, colored water, shampoo, syrup). Different solids are dropped into the column and the students are asked to observe what happens. Solids that may be dropped: buttons, plastic chips, bolts, screws, wood chips, etc. B. Lesson Proper 1. Activity: “Chemical Systems” (SAS 2-01a) Objectives: At the end of this activity, the students should be able to: Differentiate homogenous and heterogeneous systems; Give the operational definition for a homogeneous system; Record and observe data; and Make inferences. Materials: soy sauce garlic in Vinegar cooking oil in water mud and water filtered calamansi flour extract & cornstarch syrup salt and water Procedure: 1. Put each of the materials in separate test tubes and number them 1 to 8. 2. Observe their properties in terms of color, odor, phase, texture and appearance. 3. Record and tabulate your observations and classify the chemical system. BSE-Department of Education 23 2. Discussion/ Concept Formation a. Description of the Chemical Systems Chemical System Observations Classification 1. soy sauce 1 dark liquid Homogeneous 2. garlic in vinegar 1 liquid + 1 solid Heterogeneous 3. cooking oil in water 2 liquids: Heterogeneous 1 yellow, 1 colorless 4. mud and water 1 solid + 1 liquid Heterogeneous 5. filtered calamansi 1 yellow liquid Homogeneous 6. flour and cornstarch 1 white solid Homogeneous 7. syrup 1 colored liquid Homogeneous 8. salt water solution 1 colorless liquid Homogeneous b. Answer the following guide questions: i. How many phases do you see in each set-up? ii. Which systems are homogeneous? Heterogeneous? iii. How would you define a homogeneous system? a heterogeneous system? Answer: A homogeneous system is a one-phase system where all parts show the same properties all throughout; a heterogeneous system is has one or more phases in the system and each part retains its original properties. YOU MAY END SESSION 1 AT THIS POINT. 3. Activity: “Mixtures & Pure Substances” (SAS 2-01b) Objective: At the end of this activity, the student should be able to differentiate between pure substances and a mixture. Materials. Salt Water Evaporating dish Match Tripod Wire gauge Alcohol Lamp Procedure: 1. Get a small amount of salt and a glass of water. Observe their properties. 2. Pour a small amount of water into the evaporating dish and dissolve the salt in it. 3. Evaporate the solution using a water bath until almost all of the water has evaporated; the evaporating dish aside to complete the evaporation process. 4. Observe the contents after the evaporating dish has cooled. 4. Discussion/ Concept Formation a. Answer the following questions: 24 BSE-Department of Education i. What is left of the solution? Compare its properties with the original salt. ii. Were you able to get the salt from the solution? How? What kind of matter is salt? iii. Where did the water go? What type of matter was left in the dish? iv. Which of the systems is a mixture? Why? v. Define a (1) substance and (2) mixture. (A substance is made up of only one kind of molecule and cannot be separated by physical means. A mixture is made up of 2 or more kinds of molecules, which can be separated by physical means.) b. Application: Describe the production of salt by evaporation. Is the salt produced here different from what has been produced in the laboratory? YOU MAY END SESSION 2 AT THIS POINT. C. Generalization 1. Homogeneous systems are one-phase systems; all parts of the systems show the same characteristics all throughout. A heterogeneous system is a one ore more phase system; the parts retain their original properties. 2. A substance is made of only one kind of molecule; a mixture is made of 2 or more kinds of molecules. 3. Table of Mixtures Type of Mixture Filterability Particle Size Degree Settling Tyndall Effect solutions (ex. salt solution) colloids (ex. starch & water) not filterable slight filterability smallest particle size does not settle slightly dispersed NA suspensions (ex. starch & water) very filterable particle are bigger than that of solutions but smaller than suspensions biggest particle size Particles settle at the bottom Tyndall effect was observed NA D. Application / Valuing How is this kind of knowledge useful in your life? In society? In the environment? E. Evaluation a. Differentiate the types of mixtures: solutions, colloids and suspensions. b. Give other examples of mixtures and describe how each may be classified. BSE-Department of Education 25