how do i calculate a ratio of oxidised to reduced cytochrome c Fe2+ to Fe3+
given
E(mV) at 25 C and pH7 as 100
and absorbance at 550nm as 1.5
E is relative to standard hydrogen electrode
i don't know how im supposed to calculate it from this data
To calculate the ratio of oxidized (Fe3+) to reduced (Fe2+) cytochrome c, you can use the Nernst equation along with the given data. The Nernst equation relates the electrode potential of a half-cell reaction to the concentration of the involved species.
First, let's determine the standard electrode potential (E°) for the cytochrome c couple. The given E(mV) value at 25°C and pH 7 is 100 mV relative to the standard hydrogen electrode (SHE). This means that the standard electrode potential of the cytochrome c couple (E°) is +100 mV.
Next, we need to use the absorbance (A) at 550 nm to calculate the concentration ratio of Fe3+ to Fe2+. The relationship between absorbance, concentration, and molar absorption coefficient (ε) is given by the Beer-Lambert Law:
A = ε l c
Where:
A = Absorbance
ε = Molar absorption coefficient
l = Path length (usually in cm)
c = Concentration (in mol/L)
Unfortunately, without the molar absorption coefficient (ε) and path length (l) values, it is not possible to directly calculate the concentration. You may need to consult a reference or perform experimental measurements to obtain these values.
Once you have the concentration of Fe3+ and Fe2+ (assuming you have the path length and molar absorption coefficient), you can calculate the ratio of oxidized to reduced cytochrome c (Fe3+/Fe2+) by dividing the concentration of Fe3+ by the concentration of Fe2+.