June 2018 Chemistry Regents #77-79

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Question 77-79

 

 

Base your answers to questions 77 through 79 on the information below and on your knowledge of chemistry.

Fuel cells are voltaic cells. In one type of fuel cell, oxygen gas, O2(g), reacts with hydrogen gas, H2(g), producing water vapor, H2O(g), and electrical energy. The unbalanced equation for this redox reaction is shown below.

H2(g) +  O2(g) → H2O(g) +  energy

A diagram of the fuel cell is shown below. During operation of the fuel cell, hydrogen gas is pumped into one compartment and oxygen gas is pumped into the other compartment. Each compartment has an inner wall that is a porous carbon electrode through which ions flow. Aqueous potassium hydroxide, KOH(aq), and the porous electrodes serve as the salt bridge.

77 Balance the equation in your answer booklet for the reaction in this fuel cell, using the smallest whole-number coefficients. [1]

Answer-->2 H2(g)+  O2(g) → 2 H2O(g) + energy

2 H2(g)+  1  O2(g) → 2 H2O(g) + energy

78 Determine the change in oxidation number for oxygen in this operating fuel cell. [1]

Answer-->  0 to 2-

79 State the number of moles of electrons that are gained when 5.0 moles of electrons are lost in this reaction. [1]

Answer-->5.0 mol

on to Questions 80-82

 

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 51-53 Questions 54-56 Questions 57-59 Questions 60-62 Questions 63-65 Questions 66-69 Questions 70-73 Questions 74-76  Questions 77-79  Questions 80-82  Questions 83-85 
 

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