August 2017 Chemistry Regents #66-68

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Questions 66-68

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Base your answers to questions 66 through 68 on the information below and on your knowledge of chemistry.

 Wood is mainly cellulose, a polymer produced by plants. One use of wood is as a fuel in campfires, fireplaces, and wood furnaces. The molecules of cellulose are long chains of repeating units. Each unit of the chain can be represented as C6H10O5. The balanced equation below represents a reaction that occurs when C6H10O5 is burned in air.

C6H10O5 + 6O2 → 6CO2 +  5H2O heat

 66 State evidence from the equation that this reaction is exothermic. [1]

Answer-->Heat is released.

67 Explain, in terms of substances in the reaction, why the equation represents a chemical change. [1]

Answer-->The products of the reaction are different substances than the reactants.

68 Show a numerical setup for calculating the percent composition by mass of carbon in C6H10O5 (gram-formula mass 162.1 g/mol). [1]

Answer-->  ((12 * 6 )/162.1)  x100

 

Next-->Questions 69-72

Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Questions 51-52 Questions 53-54 Questions 55-58 Questions 59-60 Questions 61-65 Questions 66-68 Questions 69-72 Questions 73-77  Questions 78-81  Questions 82-85

 

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