January 2018 Chemistry Regents #78-81

Highlight to reveal answers and explanations

 

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 51-54
 Questions 55-56 Questions 57-59 Questions 60-62 Questions 63-65  Questions 66  Questions 67-69  Questions 70-72 Questions 73-77 Questions 78-81 Questions 82-85  

 

 

 

 

 #78-81
  

A student sets up a voltaic cell using magnesium and zinc electrodes. The porous barrier in the cell has the same purpose as a salt bridge. The diagram and the ionic equation below represent this operating cell.

Mg(s) + Zn2+(aq) → Zn(s)  + Mg2+(aq)

78 Determine the number of moles of Mg2+(aq) ions produced when 2.5 moles of Zn2+(aq) react completely in this cell. [1]

 HIGHLIGHT TO SEE THE ANSWER

2.5 mol

79 State, in terms of ions, how the porous barrier functions as a salt bridge in this cell. [1]

 HIGHLIGHT TO SEE THE ANSWER

ion flow

80 State, in terms of the relative activity of metals, why the reaction in this cell occurs. [1]

 HIGHLIGHT TO SEE THE ANSWER

Mg is higher on Table J.

Magnesium is more active than zinc

81 Write a balanced half-reaction equation for the oxidation that occurs in this operating cell. [1]

 HIGHLIGHT TO SEE THE ANSWER

Mg--> Mg2+ + 2e-

  

on to Questions 82-85

  

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 51-54
 Questions 55-56 Questions 57-59 Questions 60-62 Questions 63-65  Questions 66  Questions 67-69  Questions 70-72 Questions 73-77 Questions 78-81 Questions 82-85