Consider the titration of 50.00 (0.05) mL of a mixture of I and SCN with 0.068 3 (0.000 1) M Ag. The first equivalence point is observed at 12.6 (0.4) mL, and the second occurs at 27.7 (0.3) mL. 

(a) Find the molarity and the uncertainty in molarity of thiocyanate in the original mixture. 

(b) Suppose that the uncertainties are all the same, except that the uncertainty of the first equivalence point (12.6 ? mL) is variable. What is the maximum uncertainty (milliliters) of the first equivalence point if the uncertainty in SCN molarity is to be 4.0%?