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Chapter 15 Holt

Chapter 15 Holt . Chemical Reactions. Using Vocabulary. 1. Adding a(n) inhibitor will slow down a chemical reactions. 2. A chemical reaction that gives off light is called exothermic.

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Chapter 15 Holt

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  1. Chapter 15 Holt Chemical Reactions

  2. Using Vocabulary • 1. Adding a(n) inhibitor will slow down a chemical reactions. • 2. A chemical reaction that gives off light is called exothermic.

  3. 3. A chemical reaction that forms one compound from two or more substances is called a synthesis reaction.

  4. 4. The 2 in the formula Ag2S is a subscript. • 5. The staring materials in a chemical reaction are reactants.

  5. Understanding Concepts • 6. Balancing a chemical equation so that the same number of atoms of each element is found in both the reactants and the products is an illustration of • C) the law of conservations of mass.

  6. 7. What is the correct chemical formula for calcium chloride? • B) CaCl2 • Ca has a valence of 2, so 2+ charge • Cl has a valence of 7, so -1 charge • So 2 Cl- with Ca++ makes CaCl2

  7. 8. In which type of reaction do ions in two compounds switch places? • D) double-replacement • Ex: NaOH + HCl --> NaCl + H2O

  8. 9. Which is an example of the use of activation energy? • C) holding a match to paper

  9. 10. Enzymes in your body act as catalysts. The role of enzymes is to • A) Increase the rate of chemical reactions (make the reactions happen faster)

  10. Short Answers • 11. Classify each of the following reactions: • A) Fe + O2 --> Fe2O3synthesis • Balanced this would be • 4Fe + 3O2 --> 2Fe2O3 • Iron + oxygen --> rust

  11. B) Al + CuSO4 --> Al2(SO4)3 + Cu • single replacement • Balanced this is • 2Al + 3CuSO4 --> Al2(SO4)3 + 3Cu • Aluminum + cupric sulfide --> aluminum sulfide plus copper

  12. C) Ba(CN)2 + H2SO4 --> BaSO4 +HCN • Double replacement • Balanced this is • Ba(CN)2 + H2SO4 --> BaSO4 + 2HCN

  13. 12. Name two ways that you could increase the rate of a chemical reaction. • 1) raise the temperature • ( this increases the concentration and/or the surface area) • 2) add a catalyst

  14. 13. The reactants are acetic acid (vinegar) and baking soda (sodium bicarbonate). • The products are carbon dioxide CO2 , water H2O, and sodium acetate.

  15. 14. Concept map is on the white board. • Terms are: • Chemical reaction • Chemical equation • Chemical formulas • Reactants, products, • Coefficients, subscripts

  16. Critical Thinking & Problem Solving • 15. Your friend is very worried by rumors he has heard about a substance called dihydrogen monoxide. What could you say to your friend to calm his fears? • Dihydrogen H2 • Monoxide O • So H2O - not to worry - its water !

  17. 16. As long as proper safety precautions have been taken, why can explosives be transported long distances without exploding? • Explosives need to absorb energy to being the reaction. Without this absorption, they can be transported safely.

  18. Math in Science • 17. Calculate the number of atoms of each element shown in each of the following: • A) CaSO4 • Ca - Calcium - 1 atom • S - Sulfur - 1 atom • O - Oxygen - 4 atoms

  19. B) 4NaOCl • Na - sodium - 4 atoms • O - oxygen - 4 atoms • Cl - chlorine - 4 atoms

  20. C) Fe(NO3)2 • Fe - iron - 1 atom • N - nitrogen - 2 atoms • O - oxygen - 6 atoms

  21. D) 2Al2(CO3)3 • Al - Aluminum - 4 atoms • C - carbon - 6 atoms • O - oxygen - 18 atoms

  22. 18. Write balanced equations for the following: • A) Fe + O2 --> Fe2O3

  23. 18. Write balanced equations for the following: • A) Fe + O2 --> Fe2O3 • Answer: • 4Fe + 3O2 --> 2 Fe2O3

  24. B) Al + CuSO4 --> Al2(SO4)3 + Cu • Answer

  25. B) Al + CuSO4 --> Al2(SO4)3 + Cu • Answer • 2Al + 3CuSO4 --> Al2(SO4)3 + 3Cu

  26. C) • Ba(CN)2 + H2SO4 --> BaSO4 + HCN

  27. C) • Ba(CN)2 + H2SO4 --> BaSO4 + HCN • Answer • Ba(CN)2 + H2SO4 --> BaSO4 + 2HCN

  28. 19) Balanced chemical equations: • A) bromine reacts with sodium iodide to form iodine and sodium bromide • Br2 + 2NaI --> I2 + 2NaBr

  29. B) Phosphorus reacts with oxygen gas to form diphosphorus pentoxide • 4P + 5O2 --> 2P2O5

  30. C) Lithium oxide decomposes to form lithium and oxygen • 2Li2O --> 4Li + O2

  31. Interpreting Graphics • 20. In the photo on page 393, what evidence supports that this is a chemical reaction? • Answer • - Bubbles of gas are produced • - Light is given off

  32. 21. Using the energy diagram on page 393, answer q’s a,b,c • A) “C” represents the energy of the products (far right section of graph) • B) “B” represents the activation energy of the reaction (increases then peaks) • C) Energy is “given off” by this reaction. • That’s the decline of energy below starting energy mark - “D” on the chart)

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