of 61 % c 6.83 % h , 11.86? "hexabarbital used in medicine as a sedative and intrevenous anethetic, is composed of 61 % c 6.83 % h , 11.86% N, and 20.32 % O by mass. a sample of2.505 mg in 10.00 ml of solution has an osmotic pressure of 19.7 toorr at 25c. wht is the molecular formula?" help show me how to do it please