January 2009 Chemistry Regents #67-68

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Base your answers to questions 67 through 68 on the information below.

Underground iron pipes in contact with moist soil are likely to corrode. This corrosion can be prevented by applying the principles of electrochemistry. Connecting an iron pipe to a magnesium block with a wire creates an electrochemical cell. The magnesium block acts as the anode and the iron pipe acts as the cathode. A diagram of this system is shown below.

67 State the direction of the flow of electrons between the electrodes in this cell. [1]

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Electrons flow from the magnesium block to the iron pipe.

Electrons flow from the Mg to the Fe through the wire.

Electrons flow from the anode to the cathode in a voltaic cell.

from the block to the pipe

(USE TABLE J e- flow from top to bottom of the table)

68 Explain, in terms of reactivity, why magnesium is preferred over zinc to protect underground iron pipes. Your response must include both magnesium and zinc. [1]

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Mg is higher on Table J

Mg is more active than Zn.

Magnesium atoms lose electrons more easily than zinc atoms.

Mg oxidizes more readily than Zn.

on to Questions 69-71

 

Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

Questions 51-53 Questions 54-55 Questions 56-58 Questions 59-61 Questions 62-64 Questions 65-66 Questions 67-68 Questions 69-71 Questions 72-74 Questions 75-77 Questions 78-79 Questions 80-81

 
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