The figure shows the effect of pHpH on the response of a nitrite (NO2 ) (NO 2 ) ion selective electrode immersed in 1 M NaNO2 1 mM NaCLl 1 M NaNO2 1 mM NaCLl The authors recommend using the flat region near pH 5 5p H5 5 for measuring nitrite To a first approximation, we expect the electrode to resp...

a The pKa for nitrous acid is approximately 33 At pH values lower than the pKa the nitrous acid HNO2 ...

The figure shows the effect of pHpH on the response of a nitrite (NO2-) (NO - 2

Question:

The figure shows the effect of pHpH on the response of a nitrite (NO2-) (NO^-₂) ion-selective electrode immersed in 1 μM NaNO2+1 mM NaCLl. 1 μM NaNO2+1 mM NaCLl. The authors recommend using the flat region near _pH_5.5pH5.5 for measuring nitrite. To a first approximation, we expect the electrode to respond to [NO2-][NO^-₂] by the equation E=constant-(59 mV) log [NO2-].E = constant - (59 mV) log [NO^-2].
a. Look up _pKapK_a for nitrous acid and explain the behavior of the curve at _pH<4.pH < 4.
b. Suggest an explanation for the behavior at _pH>6.pH > 6.