CHEM 2121 Lecture Notes - Phenyl Group, Hlah, Akal
Document Summary
Iron(iii) thiocyanate pale yellow colorless red to write a true eqbm expression, need to express things in terms of activity. Activity: dependent on true concentration but related to activity coefficient. *ionic strength = mutotal charge in sol"n now it takes into account other ions in sol"n can also look @ solubility. The more ions you add, the more solubility increasesas shown by eqbm shifting to right. Glucose don"t do anything b/c neutralgreater the charge --> greater the effectmore solubility. Eobs = (0. 339v - (0. 05916v/2)log(1/[cu2+])) - (0. 197v) + sum[ejunction] *measured potentials actually measure activity, not actual concentrationso multiply concentration by gamma. Eobs = 0. 339v - (0. 05916v/2)log(1/gamma) - (0. 05916v/2)log(1/[cu2+]) - (0. 197v) + sum[ejunction] -> if everything else except copper concentration is constantthen voltage only depends on copper concentrationthat"s what we want we want fix activity coefficient and junction potential. So we have to fixcan"t make direct measurements.
