# How do you find the E_cell given standard E_cell, Molarity, and the chemical reaction equation?

##
Find Ecell for an electrochemical cell based on the following reaction

#[MnO_4^-]= 2.50 M#

#[H^+]= 1.50 M#

#[Ag^+]= 0.0090 M#

E∘cell for the reaction is #+0.880V#

#MnO_4^"-"(aq)+4H^+(aq)+3Ag(s)→MnO_2(s)+2H_2O(l)+3Ag^+(aq)#

Find Ecell for an electrochemical cell based on the following reaction

E∘cell for the reaction is

##### 1 Answer

#### Explanation:

Using the Nerst Equation we can can find the

The Nernst equation is

#color(blue)(bar(ul(|color(white)(a/a)E_"cell" = E⁰_"cell" - (RT)/(nF)lnQcolor(white)(a/a)|)))" "#

where

Note: the units of

The moles refer to the “moles of reaction”.

Since we always have 1 mol of reaction, we can write the units of

Calculate the number of moles of electrons transferred in the balanced equation for the cell reaction

The half reactions are

The number of electrons exchanged is 3

The

Calculate the value for reaction quotient

Substitute values into the Nernst equation and solve for

#E_"cell"# .

#E_"cell" = E_"cell" = E⁰_"cell" - (RT)/(nF)lnQ = "0.880V" – (8.314 "V"·color(red)(cancel(color(black)("C·K"^"-1"))) × 298 color(red)(cancel(color(black)("K"))))/(3 color(red)(cancel(color(black)("mol"))) × "96 485" color(red)(cancel(color(black)("C·mol"^"-1")))) × ln( 5.76e-8 ) #