The percent by mass of methanol (MM = 32.04 g/mol) in an aqueous solution is 21.1%. What is the molality of the methanol solution?

Molality of the methanol solution = 8.33 m

Explanation:

Given:

Mass % = 21.1 %

Molar mass of methanol = 32.04 g / mol

Find:

Molality of the methanol solution?

Computation:

Moles of methanol = Mass / Molar mass

Moles of methanol =  = 21.1 / 32.04

Moles of methanol = 0.658

Assume.

Mass of solution = 100 g

Mass of solvent  = 100 -21.1 = 78.9 g  = 0.0789 kg

Molality of the methanol solution = 0.658 / 0.0789

Molality of the methanol solution = 8.33 m

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.