describe the correct procedure for preparing 250 mL of .10M Ba(OH)2 from solid crystals of BA(OH)2 x 10 H2O. Assume you have all the necessary equipment and that deionized water is the solvent.
How many moles do you need in the final solution? That will be M x L = 0.250 x 0.1 = 0.0250 moles.
How many grams is that?
moles = grams/molar mass.
grams = moles x molar mass = 0.0250 x 351.49 = 8.787 g.
So you weigh accurately 8.787 g Ba(OH)2.10H2O, place in a 250 mL volumetric flask, add some water and swirl to dissolve all of the solid, then add water to the mark of the volumetric flask. Finally, shake to mix the contents of the flask thoroughly. Note that you have written 0.10 M which means two significant figures. I've weighed out more accurately than that; therefore, you may not need it that accurately.