1. Chemistry Focus Activities Chemical Formulas & Equations 8 th Grade The focus activities in this presentation are intended to provide students opportunities to:  interpret and analyze graphs  explain their reasoning when choosing an answer in multiple choice questions.

2. Teacher Instructions Choose from the focus activities provided and use as needed. Examples:  Segment the graphs and questions and use them individually or in pairs for warm-ups and exit tickets.  Incorporate the items as a group or individually into intervention strategies.  Methodically work through answers with students in support of building test taking/processing skills and assessing their logic (metacognition).  Follow-up questions could be used as prompts for journal entries. Provide students opportunities to discuss their answers with their peers.  Round Robin(write/share/add-on/pass)  Rally Table (write/share/revise)  Quiz-Quiz-Trade  Numbered Heads Together (write/share/discuss/consolidate/represent)  A-B Pair Share  Shoulder Partner (think/pair/share)  Stand Up/Hand Up/Pair Up Provide the STAAR Grade 8 Science Reference Materials (Formulas and Periodic Table of the Elements) as an anchor of support.

5. Chemical Formulas (8.5F) 8.5: Matter and energy. The student knows that matter is composed of atoms and has chemical and physical properties. The student is expected to: 8.5F: recognize whether a chemical equation containing coefficients is balanced or not and how that relates to the law of conservation of mass. Review 6.5A: know that an element is a pure substance represented by chemical symbols. 6.5C: differentiate between elements and compounds on the most basic level. 7.6A: identify that organic compounds contain carbon and other elements such as hydrogen, oxygen, phosphorus, nitrogen, or sulfur. 8.5D: recognize that chemical formulas are used to identify substances and determine the number of atoms of each element in chemical formulas containing subscripts. 8.5E: investigate how evidence of chemical reactions indicate that new substances with different properties are formed. Skills TEKS: 8.2C-E

6. Interpreting Graphs Focus Activities

7. 1. What type of graph is represented? 2. Label the x-axis with an “X” and the y-axis with a “Y”. 3. What information is provided on the x-axis? 4. What information is provided on the y-axis? 5. Which axis represents the independent variable? What was the independent variable for this experiment? 6. Which axis represents the dependent variable? What was the dependent variable for this experiment? 7. What trends do you notice on the graph? 8. Create a table from the information in the graph. Part I: Components of a Graph

8. 1. How does the volume of CO 2 change over time? 2. How long does the reaction take? 3. During the reaction, when does the maximum amount of CO 2 produced? 4. How long does it take to produce 100 cm 3 of CO 2 during the reaction? 5. What is the difference in volume of CO 2 between 200 seconds and 1200 seconds? Part II: Analyzing the Graph

9. Follow Up Discussion Questions 1.Is the chemical equation for this reaction balanced? 2.What evidence supports your position?

10. Justify Your Answer Focus Activities 1. Students read the question and select the correct answer. 2. Students write a statement for each answer selection stating why it is correct or incorrect. 3. Students choose the correct answer choice based on their analysis of each answer selection.

11. Review (6.5A): Use your periodic table as a resource. What is the elemental symbol for sodium? Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A.S This answer choice is (correct/incorrect) because… B. Na C. 11 D. N

12. Review (6.5C): Why is carbon considered to be an element, but carbon dioxide is classified as a compound? Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A.Carbon dioxide is a gas. This answer choice is (correct/incorrect) because… B. Carbon dioxide has two different elements. C. Carbon is found in living matter. D. People exhale carbon dioxide.

13. Review (7.6A): Look at the table provided. Which of the following compounds belongs in the Y Compounds column in the table? Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A.Fe 2 O 3 This answer choice is (correct/incorrect) because… B. CH 3 COOH C. C 15 H 31 CO 2 C 30 H 61 D. C 8 H 10 N 4 O 2

14. Review (8.5D): (NH 4 ) 2 CO 3 How many atoms of hydrogen (H) are found in this substance? Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A.2 This answer choice is (correct/incorrect) because… B. 4 C. 6 D. 8

15. Review (8.5D): What is the best formula for the above substance? Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A.H 2 and O 2 This answer choice is (correct/incorrect) because… B. H 2 O 2 C. H 2 O D. H 2 O 2

16. Review (8.5E): Students perform an experiment in which a crystalline substance is added to a beaker filled with water. The crystals dissolve, and a precipitate is formed. The bottom of the beaker feels warm to the touch. The temperature is monitored and the temperature data is recorded. Which observation in the above experiment tells you that a chemical reaction has occurred? Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A.A decrease in temperature This answer choice is (correct/incorrect) because… B. The crystals dissolve. C. A gas is produced. D. The formation of a precipitate

17. Review (8.5E): A crystalline substance is added to a beaker filled with water. The crystals dissolve, and a precipitate is formed. The bottom of the beaker is too hot to touch. The temperature is monitored and the temperature data is shown on the graph below. At which time did the temperature first reach 65ºC? Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A.40 This answer choice is (correct/incorrect) because… B. 48 C. 72 D. 80

18. A student writes the following chemical equation. Did the student write a balanced equation? Na 2 SO 4 +K 2 Cl  Na 2 Cl+K 2 SO 4 Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. Yes This answer choice is (correct/incorrect) because… No

19. Follow Up Discussion Questions 1.What strategy did you use to determine if the chemical equation was balanced? 2.Why must a chemical equation be balanced? 3.Which law defines this explanation?

20. Complete an atom “inventory” to decide if the following chemical equation is balanced. Sn+HF  SnF 2 +H 2 Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. Yes This answer choice is (correct/incorrect) because… No

21. Follow Up Discussion Questions Describe what occurs during a chemical reaction and how this process can be visualized by writing a chemical equation. In your description, include answers to these questions. – What are the reactants, and what occurs to them? – What are the products, and what occurs to them? – Why is it important that the chemical equation be balanced? – What must be equal in a balanced equation?

22. Complete an atom “inventory” to decide if the following chemical equation is balanced. SiO 2 +C  SiC+CO Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. Yes This answer choice is (correct/incorrect) because… No

23. Complete an atom “inventory” to decide if the following chemical equation is balanced. Al(OH) 3 +3HCl  AlCl 3 +3H 2 O Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. Yes This answer choice is (correct/incorrect) because… No

24. Which number could replace the “?” to balance this equation. H 2 +Cl 2  ?HCl Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A. 1 This answer choice is (correct/incorrect) because… B. 2 C. 3 D. 4

25. Follow Up Discussion Questions 1.How many atoms of each element are in the reactants? 2.How did you know? 3.What part of the chemical equation tells you the number of atoms in the reactants? 4.What is the “?” in the products called?

26. Which of the following is true about the Law of Conservation of Mass? Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A. Matter must first be destroyed in order to be created. This answer choice is (correct/incorrect) because… B. The mass of the products is always less than the mass of the reactants. C. The mass of the reactants must always equal the mass of the products. D. The mass of the products is always greater than the mass of the reactants.

27. Follow Up Discussion Questions 1.In your own words, define the Law of Conservation of Mass. Make sure to relate the Law of Conservation of Mass to these terms: subscripts, coefficients, products, and reactants.

28. Is the Law of Conservation of Mass conserved in this reaction? 2H 2 O → 2H 2 + O 2 Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A. Yes, because the number of atoms of each element on both sides of the equation has not changed. This answer choice is (correct/incorrect) because… B. No, the number of molecules must be the same on both sides of the chemical equation. C. No, this chemical reaction is not possible. D. Yes, because the mass of the products is always greater than the mass of the reactants.

29. Look at the following four chemical equations. Choose the correctly balanced chemical equation. Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A. 2HClO → 2H 2 O + 2Cl 2 O This answer choice is (correct/incorrect) because… B. CuO + 2HCl → 2CuCl 2 + H 2 O C. MgCl 2 + NaF → MgF 2 + NaCl D. 2C 2 H 2 + 5O 2 → 4CO 2 + 2H 2 O

30. With respect to the Law of Conservation of Mass, what is the most accurate way to describe what happens to the atoms involved in a chemical reaction? Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A. The reactant atoms are destroyed, and new product atoms are formed. This answer choice is (correct/incorrect) because… B. The reactant atoms are rearranged to form new compounds called the products. C. Nothing happens to the atoms during the reaction. D. Additional atoms are required in order to make the products.

31. Which equation best obeys the Law of Conservation of Mass? Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A. N 2 + 3H 2 --> 2NH 3 This answer choice is (correct/incorrect) because… B. H 2 + O 2 --> 2H 2 O C. 2Ag 2 O --> Ag 2 + O 2 D. N 2 + H 2 --> NH 3

32. What is wrong with the chemical equation shown below? CH 4 +O 2 -->CO 2 +H 2 O Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A. It is not balanced. It follows the Law of Conservation of Mass. This answer choice is (correct/incorrect) because… B. It is not balanced. It does not follow the Law of Conservation of Mass. C. It is a balanced equation. There is nothing wrong with it. D. It is a balanced equation. It follows the Law of Conservation of Mass.

33. Which equation below is correctly balanced? Answer Choice Justify why each answer is either correct or incorrect by drawing or writing a clear statement to show your reasoning. A. C 12 H 22 O 11 + 12O 2 --> 6CO 2 + 11H 2 O This answer choice is (correct/incorrect) because… B. 2C 12 H 22 O 11 + 12O 2 --> 24CO 2 + 11H 2 O C. C 12 H 22 O 11 + 12O 2 --> 12CO 2 + 22H 2 O D. C 12 H 22 O 11 + 12O 2 --> 12CO 2 + 11H 2 O