has a potential of 20.2094 V when the solution in the
right-hand compartment is a buffer of pH 4.006. The following potentials are
obtained when the buffer is replaced with unknowns: (a) 20.2806 V and (b)
20.2132 V. Calculate the pH and the hydrogen ion activity of each unknown. (c)
Assuming an uncertainty of 0.001 V in the junction potential, what is the range
of hydrogen ion activities within which the true value might be expected to lie?