Chemical Properties and Changes

Transcription

1 Lesson Outline LESSON 4 A. Chemical Properties 1. A(n) is a characteristic of matter that can be observed as it changes to a different type of matter. 2. The ability of a fuel to is one example of a chemical property, and the ability of iron to is another example. B. Comparing Properties 1. All matter can be described by using its properties and its properties. 2. The difference in the types of properties is whether or not the matter changed C. Chemical Changes while it was being observed. 1. A(n) is a change in matter in which the substances that make up the matter change into other substances that have new physical and chemical properties. 2. New substances that have formed no longer have the same because they no longer have the same. D. Signs of Chemical Change 1. The formation of can indicate a chemical change. 2. is released during a fireworks explosion because a chemical change occurred. 3. When fruit rots, changes in color and show that a chemical change occurred. 4. These signs of chemical change only show that a(n) might have occurred; some of these signs also occur during. 5. The only sure sign that a chemical change occurred is when new E. Explaining Chemical Reactions form. 1. Another name for a chemical change is a(n). 2. A chemical reaction occurs when atoms during a chemical change. 68 Foundations of Chemistry

2 Lesson Outline continued 3. A chemical reaction can be represented by a(n), which shows the of each substance in the reaction. a. A(n) indicates that a reaction takes place. b. The formulas to the left of the arrow in the equation represent the, which are the that were present before the reaction began. c. The formulas to the right of the arrow in the equation represent the, which are the that were present after the reaction is complete. 4. Chemical equations must be, because mass is during a chemical reaction. a. When balancing a chemical equation, you cannot change the of any reactant or product. b. To balance the equation, numbers called are placed in front of the chemical formulas. F. The Rate of Chemical Reactions 1. Higher usually increases rate of reaction because the particles move more and collide harder. 2. is the amount of substance in a certain volume. Reaction rate increases when concentration. 3. affects reaction rate if at least one is. is a solid. Reaction rate is faster if surface area Foundations of Chemistry 69

3 Content Practice A LESSON 4 Directions: Complete the concept map with the correct term from the word bank in the space provided. Each term is used only once. change in color change in energy change in odor concentration formation of bubbles surface area temperature signs of change include Chemical Change rate of reaction can be increased by Foundations of Chemistry 71

4 Content Practice B LESSON 4 Directions: Complete the chart with the correct terms on the lines provided. Balancing Chemical Equations When methane (CH 4 ) reacts with oxygen (O 2 ), the reaction produces carbon dioxide (CO 2 ) and water (H 2 O). Write and balance a chemical equation for this reaction. Step 1. Write the equation and check to see if it is balanced. a. Write the chemical formulas with the (1.) on the left side of the arrow and the (2.) on the right side of the arrow. b. Count the atoms of each (3.) in the reactants and the products. Note which elements have a balanced number of atoms on each side of the (4.). If all elements are balanced, the overall equation is balanced. If not, go to step 2. a. CH 4 + O 2 CO 2 + H 2 O b. reactants products C = 1 C = 1 (5.) H = 4 H = 2 not balanced O = 2 O = 1 (6.) Step 2. Add coefficients to the chemical formulas to balance the equation. a. Pick an element in the equation whose atoms are not balanced, such as hydrogen. Write a (7.) in front of a reactant or a product that will (8.) the atoms of the chosen element in the equation. b. Recount the atoms of each element in the (9.) and the (10.) and note which ones are balanced on each side of the equation. c. Repeat steps 2a and 2b until all atoms of each element in the (11.) equal those in the products. a. CH 4 + O 2 CO 2 + 2H 2 O b. C = 1 C = 1 (12.) H = 4 H = 4 balanced O = 2 O = 4 (13.) c. CH 4 + 2O 2 CO 2 + 2H 2 O C = 1 C = 1 (14.) H = 4 H = 4 balanced O = 2 O = 4 (15.) Is the equation balanced? (16.) 72 Foundations of Chemistry

5 School to Home LESSON 4 Directions: Use your textbook to respond to each statement. 1. Matter has chemical properties in addition to physical properties. Physical and chemical properties can be used to describe matter. Define chemical property. 2. Changes in matter can be classified as physical changes or chemical changes. All chemical changes result in the formation of a new substance, with properties that are different from the starting materials. Identify four signs that a chemical change might have occurred. 3. Mass is conserved during physical and chemical changes. Chemical equations must show that mass is conserved. Explain how the balancing of chemical equations shows that mass is conserved. 4. Some chemical changes occur rapidly, and some occur slowly. The rate of chemical reactions can be changed using methods that increase the number and energy of the collisions between particles. Describe three factors that can increase the rate of chemical reactions. Foundations of Chemistry 73

6 Key Concept Builder LESSON 4 Key Concept What is a chemical property? Directions: Complete the concept map with the correct terms in the space provided. Chemical Property examples include Directions: On the line before each phrase, write C if the phrase describes a chemical property or P if the phrase describes a physical property. 1. ability to burn 2. ability to change state 3. ability to decompose 4. ability to rust 5. ability to change shape 74 Foundations of Chemistry

7 Key Concept Builder LESSON 4 Key Concept What are some signs of chemical change? Directions: Put a check mark on the line before each sign of a chemical change. 1. change in odor 2. disappearance of a solute 3. change in energy 4. change in shape 5. formation of bubbles 6. change in state 7. change in color 8. change in size Directions: Respond to each statement on the lines provided. 9. Describe a chemical change. 10. Give an example of a common chemical change. Foundations of Chemistry 75

8 Key Concept Builder LESSON 4 Key Concept Why are chemical equations useful? Directions: Use the equation to answer each question on the lines provided. Fe + S FeS 1. What does a chemical equation show? 2. What does the part of the equation to the left of the arrow represent? 3. What does the plus sign indicate? 4. What does the arrow indicate? 5. What does the part of the equation to the right of the arrow represent? 6. What is the difference between products and reactants? 7. How are chemical equations helpful? 76 Foundations of Chemistry

9 Key Concept Builder LESSON 4 Key Concept What are some factors that affect the rate of chemical reactions? Directions: Answer each question or respond to each statement on the lines provided. 1. What happens to the particles in matter when temperature is increased? 2. How does an increase in temperature affect the rate of a chemical reaction? 3. Give an everyday example of how temperature affects rates of chemical reaction. 4. What is concentration? 5. How does an increase in concentration affect the rate of a chemical reaction? 6. Give an everyday example of how concentration affects rates of chemical reaction. 7. How does an increase in surface area affect the rate of a chemical reaction? 8. Give an everyday example of how surface area affects rates of chemical reaction. Foundations of Chemistry 77

10 Lesson Quiz B LESSON 4 Matching Directions: On the line before each definition, write the letter of the term that matches it correctly. Not all terms are used. 1. characteristic of matter that can be observed as it changes to a different type of matter 2. results in the formation of new substances 3. statement that describes a reaction A. chemical formula B. chemical change C. chemical equation D. chemical property Short Answer Directions: Respond to each statement on the lines provided. 4. Explain why chemical equations must be balanced. 5. List three signs that indicate a chemical change might have occurred. 6. Identify the evidence you would need to prove that a chemical reaction has occurred. 7. Relate the concentration of the reactants in a chemical reaction to the rate at which the reaction occurs. Foundations of Chemistry 81