CHEM 2121 Lecture Notes - Free Silver, Regrading, Galvanic Cell
Document Summary
Manipulate flow of electrons through circuit by measuring voltage and current. Fe3+ + e- --> f2+ (reduction) that electron must come from somewhere. R (beducing agent: gives up electrons, gets oxidized, reduces something else. Oxidizing agent: the opposite" accepts electrons, gets reduced. Combo of 2 redox rxns basis for potentiometry. In picture, cathode surface = agcl(s) + e- ag(s) + cl- (aq) (reduction. Cd(s) cd2+ net rxn (want electrons to cancel, so multiply agcl rxn by 2) 2agcl(s) + cd(s) cd2+ (aq) + 2ag(s) + 2cl-(aq) (net) (aq) + 2e- (oxidation) Potentiometer measures potential difference subtracts potential from negative terminal from potential in positive terminal. Ecell = e+ - e- = measured voltage. When ecell > 0, electrons flow into negative terminal. When ecell < 0, electrons flow into positive terminal. *use measured voltage to tell direction of electron flow instead of assigning anode and cathode.
