1. Chapter 14 Chemical Reactions Little book chapter 2 (page 26-54)

2. Section 1 Objectives Describe how chemical reactions produce new substances that have different chemical and physical properties. Identify four signs that indicate that a chemical reaction might be taking place. Explain what happens to chemical bonds during a chemical reaction.

3. Chemical Reactions A _________________ is a process in which one or more substances change to make one or more ____ substances. The chemical and physical properties of the substance will __________.

4. Chemical Reactions Signs of a chemical reaction: -___________ – solid substance that is formed in a solution. -___________ -Heat __________ -Electricity -_______ change -___________ formation

5. Signs of chemical reactions Nitrogen dioxide gas is formed when copper is placed into nitric acid. The dark red precipitate is called silver chromate. It is formed when potassium chromate is added to a silver nitrate solution. 5 Energy is released during some chemical reactions. Bleach reacts with the dye on the fabric and causes the color of the material to change.

6. Section 2 Objectives Interpret and write simple chemical formulas. Write and balance simple chemical equations. Explain how a balanced equation shows the law of conservation of mass.

7. Chemical Formulas The names of many ________ compounds use prefixes to express the number of ______ of each element. mono-____Hexa-6 di-2hepta-7 _____3______8 tetra-4nona-9 _____5deca-_____

8. Chemical Formulas 2 In an ______ compound the name of metallic element is written first and _____ is added to the nonmetal.

9. Chemical Equations A chemical equation is a representation of a chemical reaction in which the reactants and products are expressed as formulas. Reactant + Reactant → Product __________ are the substances that undergo the change. Products are the new ________ formed. C + O 2 → CO 2 Reactants → _________

10. 2 + 3 = 5 Antoine Lavoiser determined that the mass of the products is always _______ to the mass of the reactants. The ______________________ states that mass is neither created nor destroyed in a chemical reaction. In order to show mass is conserved an chemical equation must be __________.

11. Balanced Equations Equations need to be balanced. Matter can not be created nor ___________. This means there needs to be the same number of ______ on each side of the equation. The equation below is balanced S 8 + 12 O 2 →8 SO 3

12. Balanced Equations Subscript small numbers to the lower right of chemical symbols represent the number of _______ of each element in the molecule Coefficients large numbers in front of chemical formulas represent the number of ___________ of the substance in the reaction

13. How Many Atoms? Using coefficients and subscripts to count atoms in equations: number of atoms = coefficient X subscript Example: How many of each type of atom are represented by: 2Al 2 (SO 4 ) 3 # of Al atoms = 2 X 2 = 4 # of S atoms = 2 X 1 X 3 = 6 # of O atoms = 2 X 4 X 3 = 24

14. ` 14

15. Section 3 Objectives Describe four types of chemical reactions. Classify a chemical equation as one of four types of chemical reactions.

16. Types of Reactions A ___________ reaction is a reaction in which ____ or more substances form a single substance. (Simple → Complex) A + B → AB

17. A ___________ reaction is when a compound breaks down into _____ or more simpler substances. (Complex → Simple) AB → A + B

18. Types of Reactions Single _____________ reaction in which one element takes the place of another element in a compound. (One person breaks up a couple and goes out with one of them. A + BC→ AC + B

19. Types of Reactions Double ___________ reaction is one in which _____ different compounds exchange ________ ions and form two new compounds. AB + CD → AD + CB

20. Energy Changes Chemical energy the energy _______ in the chemical bonds of a substance. Breaking a chemical bond requires _________. During a chemical reaction, energy is either ______________

21. Section 4 Objectives Compare exothermic and endothermic reactions. Explain activation energy. Interpret an energy diagram. Describe five factors that affect the rate of a reaction.

22. Conservation of Energy Review The law of conservation of energy states neither mass or energy can be _______ or _________ in a chemical reaction. Energy can be __________ from one object to another.

23. _____________ Reaction the energy released as the products form is _________ than the energy required to break the bonds. Reaction in which energy is ______________ Exo = ___________ Examples: Fire Digestion Hand warmers IN/OUT

24. _____________ Reaction ________ energy is required to ________ the bonds in the reactants than is released by the formation of the products. Reaction in which energy is taken in Endo = ____________ Examples: Alka-seltzer Ice packets Camera

25. Reaction Rate Reaction rates tell you how _______ a reaction is going.

26. Factors That Affect Reaction Rates Temperature – Increasing temperature _________ the reaction rate. Stirring – increases the exposure of the reactant _________ the reaction rate.

27. Factors That Affect Reaction Rates Surface Area Increasing surface area _________ the reaction rate The larger the surface area, the ____ the reaction rate Concentration increasing concentration ________ the reaction rate.

28. Factors That Affect Reaction Rates C atalyst a substance that _________ the reaction rate ________ being used up in the reaction. A substance that ______ up a reaction without being permanently changed. NOT A ___________!! Ex: __________ speed up reactions in your body.

29. Get Started Many reactions occur at room temperature, but some need a “little help” to get started. You may need to add _________ (Lighting a candle) or __________ (Diesel engine) Start a reaction

30. Activation Energy ______________ ENERGY Energy needed to _________ a reaction. This is represented by an activation curve on a graph.

31. Reaction Rate & Catalyst You can speed up a reaction (rxn) rate by: Increasing ____________ Increase Surface Area Increase Concentration Using a ____________ A catalyst is a substance that speeds up a reaction without being part of the reaction. A catalyst works by _________ the amount of _________ energy required for the reaction to occur. Remember, reactions require _________________ catalyst simply lowers the amount of energy.

32. Catalyst Continued A catalyst is neither a reactant or a _____________ When you finish the reaction __ the catalyst is still there – none was used or changed in the reaction.

33. Inhibit An _______ is a substance that _____ down or stopping a reaction may sometimes be useful. Examples: Penicillin Preservatives Fungicide

34. Section 1 Review 1. Use the following terms in the same sentence: chemical reaction and precipitate. 2. Most chemical reactions: A. have starting substances that collide with each other. B. do not break bonds. C. do not rearrange atoms. D. cannot be seen. 3. If the chemical properties of a substance have not changed, has a chemical reaction occurred? 4. Steam is escaping from a teapot. Is this a chemical reaction? Explain.

35. Section 2 Review 1. Make the following statement TRUE: A chemical formula describes a chemical reaction 2. Make the following statement TRUE: The substances formed from a chemical reaction are reactants. A. have starting substances that collide with each other. B. do not break bonds. C. do not rearrange atoms. D. cannot be seen. 3. The correct chemical formula for carbon tetrachloride is: A. CCl 3 B. C 3 Cl C. CCl D. CCl 4

36. Section 3 Review 1. In your own words, write a definition for each of the following terms: synthesis reaction and decomposition reaction. 2. What type of reaction does the following equation represent? FeS + 2HCl -> FeCl 2 +H 2 S A. synthesis reaction B. double-displacement reaction C. single-replacement reaction D. decomposition reaction 3. Describe the difference between single- and double- displacement reactions. 4. Write the balanced equation in which potassium iodide, KI, reacts with chlorine to form potassium chloride, KCl, and iodine.

37. Section 4 Review 1. Make the following TRUE: An exothermic reaction absorbs energy. 2. Make the following TRUE: The rate of a reaction can be increased by adding an inhibitor. 3. Which of the following will not increase the rate of a reaction? A. adding a catalyst B. increasing the temperature of the reaction C. decreasing the concentration of reactants D. grinding a solid into powder 4. How does the concentration of a solution affect the rate of the reaction?