Fire Unit

1. Fire Unit Investigation II: Conditions for Change Lesson 1: No Smoking Zone Lesson 2: You’re Fired! Lesson 3: All-A-Glow Lesson 4: Fuelish Choices Lesson 5: Sparklers Lesson 6: Kablooie!

2. Fire Unit – Investigation II Lesson 1: No Smoking Zone

3. ChemCatalyst • What conditions are necessary for a fire to take place? Describe at least two situations that result in fire. Unit V • Investigation II

4. The Big Question • What are the necessary questions for fire to exist? Unit V • Investigation II

5. You will be able to: • Describe the conditions necessary to support a fire. Unit V • Investigation II

6. Activity • Purpose: By observing a series of demonstrations you will explore the conditions that lead to fire. (cont.) Unit V • Investigation II

7. (cont.) Unit V • Investigation II

8. Making Sense • Pick three things from the list below to build a fire. Explain your choices. • water • aluminum • helium • sugar • oxygen • wax • match • coal Unit V • Investigation II

9. Notes (cont.) Unit V • Investigation II

10. (cont.) • Combustion reaction: The reaction of a fuel with oxygen, resulting in the production of heat and light. Unit V • Investigation II

11. Check-In • There is a small fire in the trashcan in your classroom. Name three things your teacher can do to put out the fire. Explain how each method works. Unit V • Investigation II

12. Wrap-Up • Combustion is defined as a reaction of a fuel with oxygen, which releases heat and light. • Dry fuel, a spark of some sort, and oxygen are the three items necessary for combustion. • Limiting the supply of oxygen, or adding water, extinguishes fires. (cont.) Unit V • Investigation II

13. (cont.) • Cigarette smoking is a form of combustion that has many by-products, several of them harmful to your health. Unit V • Investigation II

14. Fire Unit – Investigation II Lesson 2: You’re Fired!

15. ChemCatalyst • Name three substances that will combust or burn. • Name three substances that do not combust. Unit V • Investigation II

16. The Big Question • How can we predict whether or not a substance is combustible? Unit V • Investigation II

17. You will be able to: • Identify several properties that help us determine whether a substance will be combustible or not. Unit V • Investigation II

18. Activity • Purpose: The goal of this lesson is to allow you to make generalizations about substances that combust and substances that do not combust. (cont.) Unit V • Investigation II

19. Unit V • Investigation II

20. (cont.) Unit V • Investigation II

21. Making Sense • Based on your data, what generalizations can you make about substances that combust? • What generalizations can you make about substances that do not combust? Unit V • Investigation II

22. Notes (cont.) Unit V • Investigation II

23. (cont.) • Most ionic compounds are not combustible. • Most molecular covalent compounds are combustible (especially those that contain carbon and hydrogen). These compounds make good fuels. • Most metallic compounds are combustible. (cont.) Unit V • Investigation II

24. (cont.) • Substances that contain a high percentage of oxygen atoms may not be combustible because they may not be able to react with any more oxygen. • Water and carbon dioxide do not combust. Unit V • Investigation II

25. Check-In • Which of the following substances are likely to combust? What is your reasoning? • CH4, methane • CaBr2, calcium bromide • Na, sodium Unit V • Investigation II

26. Wrap-Up • Most ionic salts do not combust. • Most molecular covalent compounds do combust. • Most metals combust. Most metals do not produce a flame when they combust. Most metals combust very slowly. • Substances that already contain a high percentage of oxygen atoms are less apt to be combustible. • Carbon dioxide and water do not combust. They are the products of combustion. Unit V • Investigation II

27. Fire Unit – Investigation II Lesson 3: All-A-Glow

28. ChemCatalyst • The following table shows the balanced chemical equations for four combustion reactions. • List three patterns you notice. Unit V • Investigation II

29. The Big Question • How do we write a chemical equation for a combustion reaction? Unit V • Investigation II

30. You will be able to: • Write the balanced equations for various kinds of combustion reactions. Unit V • Investigation II

31. Notes • C2H6 + O2  CO2 + H2O Unit V • Investigation II

32. Activity • Purpose: The goal of this lesson is to allow you to examine chemical equations that describe combustion reactions. (cont.) Unit V • Investigation II

33. (cont.) (cont.) Unit V • Investigation II

34. (cont.) (cont.) Unit V • Investigation II

35. (cont.) Unit V • Investigation II

36. Making Sense • What are the products of the combustion of carbon-containing molecules? • What are the products of the combustion of metals? • What are the products of the combustion of salts? Unit V • Investigation II

37. Check-In • Pick a substance that combusts from the list below and write the balanced chemical reaction. • Ar • Al • C • CH4O Unit V • Investigation II

38. Wrap-Up • The products of the combustion of carbon-containing molecules are carbon dioxide and water. • Flames are gases emitting light. Flames are the result of gases that are produced during a combustion reaction. (cont.) Unit V • Investigation II

39. (cont.) • In a combustion reaction, the longer the carbon chain in the fuel, the more oxygen it reacts with. • The products of the combustion of metals are solid metal oxides. These reactions usually do not produce enough gases to support a flame. Unit V • Investigation II

40. Fire Unit – Investigation II Lesson 4: Fuelish Choices

41. ChemCatalyst • Standard automobiles use a mix of carbon-based compounds (high in octane) as fuel. The cars that race in the Indianapolis 500 use methanol as fuel. And top dragsters use nitromethane as fuel. • Balance the equations for the combustion of these fuels. • Why do you think they use different fuels for different types of driving? Unit V • Investigation II

42. Notes • (Below are the balanced chemical equations for these combustion reactions): • (octane) • C8H18 + O2 CO2 + H2O • (methanol) • CH4O + O2 CO2 + H2O • (nitromethane) • CH3NO2 + O2 CO2 + H2O + NO2 Unit V • Investigation II

43. The Big Question • What properties of a substance can be used to predict its usefulness as a fuel for combustion? Unit V • Investigation II

44. You will be able to: • Identify the properties of substances that would make them good fuels for combustion. Unit V • Investigation II

45. Activity • Purpose: In this activity, you will compare fuels to one another by examining their combustion reactions and calorie output. (cont.) Unit V • Investigation II

46. Unit V • Investigation II

47. Unit V • Investigation II

48. Making Sense • Do you think the best fuel is the one that has the greatest energy output in calories per mole? Explain your reasoning. Unit V • Investigation II

49. Notes • kilocalories or kcal: 1 kcal is equal to 1000 calories. It is also equal to 1 food Calorie • kiloJoule or kJ: 1 kJ is equal to 4.184 kcal. Joules are the metric units in common use by scientists. Unit V • Investigation II

50. Check-In • Which molecule of the three listed below would you expect to release the most energy per mole of fuel combusted? What is your reasoning? • propane, C3H8 • propanol, C3H8O • pentane, C5H12 Unit V • Investigation II