4. it was mentioned in the introduction section that the "bath tub ring" is actually the results of forming calcium, magnesium, and/or iron salts with the fatty acid salts present in the soap. a. what is the magnitude of the charge (+1, +2, or +3) on the cation of each of these metals? calcium: magnesium: iron: b. write the correct formula for the calcium, magnesium, and iron salts that would form with stearic acid, ch3(ch2)16cooh. (hint: the overall electric charge in a salt is zero). chs(ch2)16coo-na example: formula for the sodium salt of stearic acid is calcium salt: magnesium salt: iron salt: