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### Course: Chemistry library>Unit 14

Lesson 2: Galvanic cells

# 2015 AP Chemistry free response 1d

Calculating which metal will transfer more electrons in a metal-air battery. From 2015 AP Chemistry free response 1d.

## Want to join the conversation?

• I'm confused as to what the voltage is and why it doesn't come into play in the problem. What is voltage, and what does it mean in the context of these reactions?
Thank you.
• My understanding is that voltage is the willingness of the reaction to occur and is used to determine in which direction a reaction would occur. The question is asking for the number of electrons that result from 1 g of metal in the reaction, so the voltage is thus irrelevant.
• Why isn't the mol/g multiplied by how many electrons are present in the reaction? I got the same answer as Sal, but I structured my stoichiometry different.... Is it incorrect to do so?
(1 vote)
• He did account for that in his equations, see the "mol e-" term.

There's often multiple ways to arrive at the correct answer for these questions.
(1 vote)
• why Na + OH- gives Na2O but not NaOH+e-
(1 vote)
• When it comes to chemical reactions, you don't need to balance individual elements or ions of reactions. See a bigger picture.

2Na+ + 2OH- = Na2O + H2O
# of Na: 2(left) = 2(right)
# of O : 2(left) = 2(right)
# of H : 2(left) = 2(right)

Balancing a chemical equation isn't different from balancing a mathematical equation.
(2x+3y)+(3x+2y) = (4x+1y)+(1x+4y)
What matters is the total number of a variable on both sides than some part of them
(1 vote)
• Is this right for me to write down 2H2SO4 instead of either 2H+ + 2HSO4- / 4H+ + 2SO4^2- ?