You will need
- - the periodic table;
- formula to calculate the mass fraction.
Calculate the mass fraction by definition. As the mass of the substance consists of masses of elements that compose it, then share any item you have some of the mass of a substance. The mass fraction of the solution is equal to the ratio of the mass solute to the mass of the entire solution.
The mass of solution is equal to the sum of the masses of the solvent (usually water) and substances. The mass fraction of the mixture is equal to the ratio of the mass of a substance to the weight of the mixture containing the substance. Multiply the result by 100%.
Find the mass percentage yield using the formula ω=MD/MP, where MP and MD - value is estimated and obtained actual output of matter (mass), respectively. Calculate the estimated weight of the reaction equations, using the formula m=nM, where n is the chemical amount of substance, M is the molar mass of the substance (the sum of the atomic masses of all the elements in a substance), or formula m=Vρ, where V is the volume of the substance, ρ is its density. Number substances in turn if necessary, replace the formula n=V/Vm or also find from the equation of the reaction.
Mass fraction of element in compound calculate using the periodic table. Fold the atomic masses of all elements in the substance, if necessary damnosa on indices. You will get the molar mass of the substance. Find the molar mass of an element from the periodic table. Calculate the mass percentageby dividing the molar mass of the element by the molar mass of the substance. Multiply by 100%.
Pay attention to the physical process, which is the place to be. By evaporation do not count mass fraction as solution (water or other liquid) no. Don't forget that with the concentration, otherwise called a partial evaporation, the mass fraction of a substance is increased. If you dilute a concentrated solution, the mass fraction decreases.