A mixture of methanol (methyl alcohol) and water contains 40.00% water by mass. Ideal Specific Gravity - Your answer is partially correct. The specific gravity of water at 20C is about 0.9982 ; the specific gravity of methanol at 20C is about 0.7917. Assuming volume additivity of the components, estimate the specific gravity of the mixture at 20C.SG= What volume of this mixture is required to provide 450.0 mol of methanol? liters