August 2010 Chemistry Regents #70 to 72

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Base your answers to questions 70 through 72 on the information below.

Hydrogen peroxide, H2O2, is a water-soluble compound. The concentration of an aqueous hydrogen peroxide solution that is 3% by mass H2O2 is used as an antiseptic. When the solution is poured on a small cut in the skin, H2O2 reacts according to the balanced equation below.

2H2O2 ==>2H2O + O2

70 Identify the type of chemical reaction represented by the balanced equation. [1]

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decomposition

redox

71 Calculate the total mass of H2O2 in 20.0 grams of an aqueous H2O2 solution that is used as an antiseptic. Your response must include both a numerical setup and the calculated result. [2]

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SET UPS  (1 point)

 3=  (x/20.0g) x 100%

or    (20)(0.03)

Answer  0.6g  (1 point)

72 Determine the gram-formula mass of H2O2. [1]

Answer=34g/mol (no sig figs)

H2O2 ;  H= 2(1)   O=2(16)

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Questions 51-53 Questions 54-56 Questions 57-58 Questions 59-60 Questions 61-63 Questions 64-66 Questions 67-69 Questions 70-72 Questions 73-74 Questions 75-78 Questions 79-81

 
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