Chemical reaction (Pre test)

Grade 10 4th Quarter Unit 2

1. CHEMICAL REACTION

2. Learning Competencies/Objectives The learner should be able to: 1. Write chemical equations; 2. Apply the principles of conservation of mass to chemical reactions; 3. Classify reactions according to the different types; 4. Identify the factors that affect reaction rates and explain them according to collision theory; and 5. Explain how the factors affecting rates of chemical reactions are applied in food preservation and materials production, re control, pollution, and corrosion.

3. Pre-Assessment Multiple Choice. Choose the correct answer. 1 . During a chemical reaction, A. atoms are destroyed B. atoms are rearranged C. elements are destroyed D. new elements are produced

4. 2. A chemical reaction is a process in which all reactants change state products change into reactants the law of conservation of mass applies all of these

5. 3. What determines an atom’s ability to undergo chemical reactions? Protons Neutrons innermost electrons outermost electrons

6. 4. How is a chemical equation is balanced ? changing subscripts erasing elements as necessary adding coefficients adding elements as necessary

7. 5. What are the products in the equation below? Zn + CuSO 4 -----> ZnSO 4 + Cu A. Zn and Cu B. Zn and CuSO 4 C. ZnSO 4 and Cu D. Zn only

8. 6 . What determines an atom’s ability to undergo chemical reactions? Protons Neutrons innermost electrons outermost electrons

9. 6 - 10. Write TRUE if the statement is correct and FALSE if incorrect and change the underlined word/s to make the statement correct. 6. Generally , the higher the concentration of the reacting substances, the faster is the reaction.

10. 7. At lower temperature, chemical reactions occur at slower rates. 8. The bigger the surface area of the reactants, the faster the rate of reaction.

11. 9. Catalysts increase the rate of reaction by providing a reaction pathway with a higher activation energy . 10. The minimum energy required to start a reaction is called bond energy .

12. 11 - 12 Balance the following chemical equations, then classify the reaction according to its type

13. 9. Catalysts increase the rate of reaction by providing a reaction pathway with a higher activation energy . 10. The minimum energy required to start a reaction is called bond energy .

14. 13-15 Explain in concise and brief sentences. 13. What is the function of MnO2 in the production of oxygen from hydrogen peroxide in this reaction:

15. 14.Why would iron fillings rust faster than an iron nail? 15. Enzymes are in molds and bacteria that spoil food. Explain, using your knowledge of factors affecting the rate of reaction, why food doesn’t spoil as fast when it is refrigerated as it would at room temperature.

16. Pre-Assessment Multiple Choice. Choose the correct answer. 1 . During a chemical reaction, A. atoms are destroyed B. atoms are rearranged C. elements are destroyed D. new elements are produced

17. 2. A chemical reaction is a process in which all reactants change state products change into reactants the law of conservation of mass applies all of these

18. 3. What determines an atom’s ability to undergo chemical reactions? Protons Neutrons innermost electrons outermost electrons

19. 4. How is a chemical equation is balanced ? changing subscripts erasing elements as necessary adding coefficients adding elements as necessary

20. 5. What are the products in the equation below? Zn + CuSO 4 -----> ZnSO 4 + Cu A. Zn and Cu B. Zn and CuSO 4 C. ZnSO 4 and Cu D. Zn only

21. 6 - 10. Write TRUE if the statement is correct and FALSE if incorrect and change the underlined word/s to make the statement correct. 6. Generally , the higher the concentration of the reacting substances, the faster is the reaction . TRUE

22. 7. At lower temperature, chemical reactions occur at slower rates. TRUE 8. The bigger the surface area of the reactants, the faster the rate of reaction. TRUE

23. 9. Catalysts increase the rate of reaction by providing a reaction pathway with a higher activation energy . LOWER REACTION ENERGY (FALSE) 10. The minimum energy required to start a reaction is called bond energy . ACTIVATION ENERGY (FALSE)

24. 11 - 12 Balance the following chemical equations, then classify the reaction according to its type

25. 13 . MnO2 ( Manganese dioxide acts as a catalyst, it hastens the decomposition of hydrogen peroxide) 14.Iron lings rust faster because of its bigger surface area the bigger the surface area the faster the reaction rate.

26. 15.Enzymes are biological catalysts. Enzymes in molds and bacteria cause food to spoil faster. Putting food inside the refrigerator slows down spoilage due to lower temperature. The higher the temperature the higher the reaction rate. The lower the temperature the slower the reaction rate.