Chapter 23 - Redox and electrode potentials Flashcards
What does an oxidising agent do?
takes electrons from the species being oxidised
what is a reducing agent
adds electrons to the species being reduced
what is the formula of a manganate ion?
MnO4 (-1)
what is the formula of a thiosulfate ion?
S2O3 (2-)
what is an electrochemical cell made of?
two half cells
what does a half cell contain?
an element in two oxidation states
what are the three versions of half cells?
- a metal placed in an aqueous solution of one of its ions
- a non-metal in contact with a solution containing one of its ions
- a metal ion in solution, in contact with a metal ion in another oxidation state
why is a platinum electrode used?
to allow electrons in and out the cell
platinum is inert
what is the purpose of a salt bridge?
allows ions to be transferred between the half cells which allows the current to flow
what is the e.m.f?
the electromotive force and it is the voltage produced by a cell when no current flows and it tells us how easily a cell loses electrons
how do you find the e.m.f?
we compare the half cells with a standard hydrogen half cell under standard conditions
what is the standard electrode potential?
the e.m.f of a half cell compared with a standard hydrogen half cell, measured at 298K with solution concentrations of 1 mol/dm and a gas pressure of 100KPa
Finish the sentence: the more negative the standard electrode potential, the…
…greater the tendency to lose electrons/be oxidised
Finish the sentence: the more positive the standard electrode potential, the…
…greater tendency to gain electrons/be reduced
which way do electrons flow?
from negative to positive
what is the equation for standard cell potential?
E • positive terminal - E• negative terminal
what are primary cells?
non-rechargeable cells
electrical energy is produced by oxidation and reduction
what is a secondary cell?
rechargeable cells
what are fuel cells?
uses the energy from the reaction of a fuel with oxygen to create a voltage
