How to find the mass fraction of substance

People depending on the nature of their profession have to deal with solutions that have a strictly specified concentration of a solute: preparation of drug solutions, the dissolution of the developer for photos, solution for battery maintenance sulfuric acid, etc. in chemistry students with tasks learn how to calculate mass percentage of solute is the ratio of the mass solute to the total weight of the solution.

Instruction

1. Read carefully the task. Briefly on the left side of the page, record the data using letter symbols and formulas of chemicals, if any. Identify the problem that needs to be found.
2. Write down on the right side of the sheet a General formula for the mass fraction of the solute
   ω = m1 / m,
   where m1 is the mass of the solute, and m the mass of the entire solution.
   
   If the content of the mass fraction of solute need to find the percentage, multiply the resulting number by 100%:
   ω = m1 / m x 100%
3. In applications where the need to calculate the mass fraction of each of the elements included in the chemical substance, use the table of D. I. Mendeleev. For example, find the mass fraction of each of the elements included in the composition of the hydrocarbon, formula C6H12 which
   
   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 (N) = 12 m1(N) / m (C6H12) x 100% = 12 x 1 g / 84 g/mol x 100% = 15%
4. Write down the answer to the problem.