J.R. S. answered 04/16/20
Ph.D. University Professor with 10+ years Tutoring Experience
Al(NO3)3(aq) + 3KOH(aq) ==> 3KNO3(aq) + Al(OH)3(s) ... balanced equation
50.00 g Al(OH)3 x 1 mol/78 g = 0.744 moles Al(OH)3 desired
0.744 mol Al(OH)3 x 1 mol Al(NO3)3 / mole Al(OH)3 = 0.744 moles Al(NO3)3 needed
Volume Al(NO3)3 needed: (x L)(0.200 mol/L) = 0.744 moles and x = 3.72 L