A voltaic cell is constructed based on the following reaction and initial concentrations:
Fe2+ (0.0050M) + Ag+ (2.2M) -> Fe3+ (0.0050M) + Ag(s)
calculate [Fe2+] when the cell reaction reaches equilbrium
i'm so confused. please help. thank you!
Kc =[ Fe+3] / [Fe+2][Ag+]
You must be given the equilibrium constant or have access to enough information to calculated it. Since you have the initial concentrations of Fe^+2, Ag^+ and Fe^+3 with a known Kc, you can set up a table of data leadinf to an equation for changes in concentrations, that will lead to the equilibrium concentrations. I will not get into it with more info about the Kc.
To calculate the concentration of Fe2+ when the cell reaction reaches equilibrium, you need to use the principles of equilibrium and the Nernst equation. Here are the steps you can follow to solve this problem:
Step 1: Write the balanced cell reaction.
The given balanced reaction is:
Fe2+ (0.0050M) + Ag+ (2.2M) -> Fe3+ (0.0050M) + Ag(s)
Step 2: Write the Nernst equation.
The Nernst equation relates the cell potential to the activities (concentrations) of the species involved in the reaction. For this half-cell reduction reaction (Fe2+ to Fe3+), the Nernst equation is:
Ecell = E°cell - (RT/nF) * ln(Q)
Where:
Ecell is the cell potential (in volts)
E°cell is the standard cell potential (in volts)
R is the ideal gas constant (8.314 J/(mol·K))
T is the temperature in Kelvin (in this case, you need to convert to Kelvin)
n is the number of electrons transferred in the balanced cell reaction
F is the Faraday constant (96,485 C/mol)
ln is the natural logarithm
Q is the reaction quotient
Step 3: Determine the standard cell potential.
The standard cell potential (E°cell) can be found in tables or calculated using standard reduction potentials. For this reaction, the standard reduction potential for Fe3+/Fe2+ is typically around +0.77V. However, the problem does not specify the standard potential, so let's assume it to be +0.77V for now.
Step 4: Calculate the reaction quotient.
The reaction quotient (Q) is calculated using the concentrations of the species involved in the reaction. Based on the given concentrations, the reaction quotient is:
Q = ([Fe3+]/[Ag]) * ([Ag+] / [Fe2+])
Step 5: Calculate the cell potential at equilibrium.
To calculate the cell potential (Ecell) at equilibrium, substitute the values from the problem into the Nernst equation. You'll need to convert the temperature to Kelvin.
Step 6: Solve for [Fe2+] at equilibrium.
Rearrange the Nernst equation to solve for the concentration of Fe2+. You can make use of logarithm properties to isolate the variable.
By following these steps, you should be able to calculate the concentration of Fe2+ when the cell reaction reaches equilibrium.