Starting with solid kcl and water, how many grams of kcl are needed to prepare 3.00 liters of a 2.00 m kcl solution?

One mol of KCl (potassium chloride) is 74.5 gram  (molar mass is 74.5 gram/mol).
First, let's calculate the total number of moles in this solution:
n = C * V = 2 Mol/L  * 3 L = 6 mol

Then we convert to gram
1 mol ==> 74.5 gram
6 mol ==> 74.5 * 6 = 447 gram of KCl

To prepare 3 liters of 2M KCl solution, you need to dissolve 447grams of KCl in 3 liters of distilled water.