Hello, I have no idea how to solve this... The initial mass of an unknown sample containing iron (II) is 0.512 g. 12.6 mL of 0.01522 M KMnO4 is required to titrate the unknown to the endpoint. a) How many moles of MnO4- were added? b) How many moles of iron (II) must be present in the sample? c) How many grams of iron (II) must be present in the sample? d) What is the percent of iron present in the sample? I would know b, c, d, if I would know how to solve a. b, c, d, questions are simple, but I totally don't understand how to solve a. I wrote the rest so people who don't know similar exercise could get something more out of that topic. I know I shouldn't ask such a basics here, but I spent like an hour on YouTube and internet with no success. My professor is very unclear on every topic. Thank you so much for helping.