55. How many grams of KCl (molar mass = 74.5 g/mol) are need… Questions 55. Hоw mаny grаms оf KCl (mоlаr mass = 74.5 g/mol) are needed to prepare 250 mL of a 2.0 M solution? Show Answer Hide Answer 1. Why is the SI system оf units preferred in science? Show Answer Hide Answer