redox and cells Flashcards
define oxidation
the process that loses electrons
if you increase the oxidation state thats oxidation
define reduction
the process that gains electrons
decrease in oxidation state
whats an oxidising agent
electron acceptor
whats an reducing agent
electron donor
how to differentiate the strongest adn weakest oxidising agent and reducing agent in an electrochemical series
- stronger reducing agent = more negative value and the one that loses the e-
-stronger oxidising agent = more positive value and the one that gains the e-(ion)
-weaker oxidising agent = more negative value and gains e- (ion)
-weaker reducing agent = more positive and loses e-
what is the purpose of solid metal/ platinum used in a cell
-its where the half-equations occur so theyre called half cells.
-platinum is used as it conducts electricty and is unreactive
what is the purpose of a salt bridge in a cell
allows movement of ions
what are the standard conditions of the standard hydrogen electrode
-1 moldm-3 HCl(pH=0)
-100 kPa pressure
-298K temperature
-the electrode potential of the standard hydrogen is 0
how to know if a feasible half equation can be made
-there has to be a more negative value from one half equation and a more positive value from the other
-the more positive one goes has the forward reaction
-the more negative one has the backward reaction
explain why a reaction is feasible or not using the template
the Eθ for the (X+/X) half equation is more positive than the Eθ for the(Y+/Y) half equation.
therefore the (X+) is reduced to (X). and (Y) is oxidised to (Y+)
how to calculate the Eθ cell and determine if a reaction will be feasible or not
Eθ cell = more positive Eθ value - more negative Eθ value
if the Eθ cell value is positive then its feasible if its negative its not feasible
how do you make the Eθ cell more positive
-make the positive half cell more positive
-make the negative half cell more negative
how do you make the Eθ cell more negative
-make the positive half cell more negative
-make the negative half cell more positive
Zn2+ + 2e- —> Zn Eθ=-0.76
Cu2+ + 2e- —> Cu Eθ=+0.34
what would happen if conc of Cu2+ was lowered?
-Equilibrium shifts to the left to increase the concentration of Cu2+.
-The Eθ for the Cu2+/Cu half equation becomes more negative
- The Eθcell becomes more negative, the reaction is less feasible
Zn2+ + 2e- —> Zn Eθ=-0.76
Cu2+ + 2e- —> Cu Eθ=+0.34
what would happen if the conc of Cu2+ was raised
-Equilibrium shifts to the right to decrease the concentration of Cu2+.
-The Eθ for the Cu2+/Cu half equation becomes more positive
-The Eθcell becomes more positive, the reaction is more feasible
