  # A mixture of methanol (methyl alcohol) and water contains 70.00 % water by mass.The specific gravity of water at 20°C is about 0.9982; the specific gravity of methanol at 20°C is about 0.7917.I worked out the specific gravity of the mixture to be 0.958.What is the volume of the solution required to provide 200.0 moles of methanol?

Question

A mixture of methanol (methyl alcohol) and water contains 70.00 % water by mass.
The specific gravity of water at 20°C is about 0.9982; the specific gravity of methanol at 20°C is about 0.7917.
I worked out the specific gravity of the mixture to be 0.958.

What is the volume of the solution required to provide 200.0 moles of methanol?

check_circleExpert Solution
Step 1

It is given that a mixture of methanol (methyl alcohol) and water contains 70.00 % water by mass.

Basis: 100 grams of mixture

Hence mass of water present in mixture is: 70 gm

Mass of methanol in mixture is: 30 gm

And it is given that specific gravity of water at 20°C is about 0.9982; the specific gravity of methanol at 20°C is about 0.7917.

Assuming water as reference substance in the calculations of density from the specific gravity and assuming the density of water at the temperature 20°C is 1 g/cm3.

Specific gravity of any substance is the ratio of the density of the substance at any temperature to the density of reference substance at the same temperature. Hence from the specific gravity’s formula, densities are calculated at 20°C as below:

Step 2

Hence

The volumes of the methanol and water in the mixture are given below:

Step 3

From volume additivity, the volume of the mixture will be addition of volume of methanol and the volume of water at 20&...

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