People, depending on the type of their profession, have to deal with solutions that have a strictly specified content of solute in them: preparation of medicinal solutions, dissolving a developer for photographs, a solution for a battery containing sulfuric acid, etc. Therefore, in chemistry lessons, using tasks, students learn to calculate the mass fraction of solutes - the ratio of the mass of a solute to the total mass of a solution.
Read the problem carefully. Briefly, on the left side of the page, write down its details using the letter symbols and chemical formulas, if any. Determine from the problem question what to find.
Write down on the right side of the sheet the general formula for the mass fraction of the solute
ω = m1 / m, where m1 is the mass of the solute, and m is the mass of the entire solution.
If you need to know the content of the mass fraction of the solute as a percentage, multiply the resulting number by 100%:
ω = m1 / m х 100%
In tasks where you need to calculate the mass fractions of each of the elements that make up a chemical, use the table of D.I. Mendeleev. For example, find out the mass fractions of each of the elements that make up the hydrocarbon, the formula of which is C6H12
m (C6H12) = 6 x 12 + 12 x 1 = 84 g / mol
ω (C) = 6 m1 (C) / m (C6H12) x 100% = 6 x 12 g / 84 g / mol x 100% = 85%
ω (H) = 12 m1 (H) / m (C6H12) x 100% = 12 x 1 g / 84 g / mol x 100% = 15%
Write down the answer to the problem.