Right hand side of cell was titrated with Nh3 while monitoring cell voltage:
Ag(s)IAg^+ (aq, 0.1 M, 25.0 mL)II Ag^= (aq, 0.1 M, 75.0 mL)I Ag(s)
With 1.52 M ammonia titrant, the end point was observed at 9.8 mL. The measured cell voltage was near -0.15 V at the end point.
A) what are half reactions, net reaction and nernst equation for the cell
B) at end point if there is no Ag^= left, find correct stoichiometric coefficient (x) of the observed reactions of titration.
Ag^= (aq) + xNH3 (aq) --> (NH3)xAg^+ (s)
c) From observed voltage, find concentration of uncomplexed Ag^+ at the end points.
A) To determine the half reactions, net reaction, and Nernst equation for the cell, we need to break down the given chemical equation.
The half reactions involve the oxidation and reduction of the species involved in the cell.
On the left-hand side of the cell:
Oxidation half-reaction:
Ag(s) → Ag^+ (aq) + e^-
On the right-hand side of the cell:
Reduction half-reaction:
Ag^= (aq) + NH3 (aq) → (NH3)xAg^+ (s) + H2O (l) + e^-
The net reaction is obtained by combining the oxidation and reduction half-reactions:
Ag(s) + Ag^= (aq) + NH3 (aq) → (NH3)xAg^+ (s) + H2O (l)
The Nernst equation can be used to calculate the cell voltage. It relates the cell voltage (E) to the standard cell potential (E°), the concentration of species involved, and the number of electrons transferred in the balanced equation. The Nernst equation for this cell can be written as:
E = E° - (RT / nF) * ln(Q)
Where:
E = Cell voltage
E° = Standard cell potential (given)
R = Gas constant (8.314 J/(mol·K))
T = Temperature in Kelvin
n = Number of electrons transferred (calculated from the balanced equation)
F = Faraday's constant (96485 C/mol)
Q = Reaction quotient (concentrations of species involved)
B) At the endpoint, if there is no Ag^= left, we can use the stoichiometric coefficient (x) in the observed reaction of titration to determine the balanced equation.
The balanced equation for the observed reaction is:
Ag^= (aq) + xNH3 (aq) → (NH3)xAg^+ (s)
At the endpoint, all of the Ag^= reacts, so the stoichiometric coefficient that balances the reaction is x = 1.
C) From the observed voltage, we can calculate the concentration of uncomplexed Ag^+ at the endpoint using the Nernst equation.
Given:
Measured cell voltage = -0.15 V
We can rearrange the Nernst equation as follows:
E = E° - (RT / nF) * ln(Q)
Q = e^((E° - E) * (nF / RT))
Substituting the values:
E° = Standard cell potential (look up the value)
E = Measured cell voltage (-0.15 V)
n = Number of electrons transferred (calculated from the balanced equation, in this case, 1)
R = Gas constant (8.314 J/(mol·K))
T = Temperature in Kelvin
F = Faraday's constant (96485 C/mol)
Using the appropriate values, you can calculate the reaction quotient (Q) and then use Q to find the concentration of uncomplexed Ag^+ at the endpoint.
Note: Make sure to convert temperatures to Kelvin and use consistent units for all variables.