The mass fraction is a percentage of a component in mix or an element in substance. Not only school students and students face tasks on calculation of a mass fraction. The ability to calculate percentage concentration of substance finds quite practical application and in real life - where drawing up solutions is required - since construction and finishing with cookery.
It is required to you
- - Mendeleyev's table;
- - formulas for calculation of a mass fraction.
Instruction
1. Calculate a mass fraction by definition. As weight substances develops of the mass of elements which makes it, some part of mass of substance falls to the share of any making element. The mass fraction of solution is equal to the relation of mass of the dissolved substance to the mass of all solution.
2. The mass of solution is equal to the sum of mass of solvent (usually waters) and substances. The mass fraction of mix is equal to the relation of mass of substance to the mass of the mix containing substance. Increase the received result by 100%.
3. Find a mass fraction of an exit by means of a formula ω=mд/mп where mp and md - the size of the estimated and valid gained access of substance (weight) respectively. Calculate estimated weight from the reaction equation, using a formula m=nM where n is chemical amount of substance, M - the molar mass of substance (sum of atomic masses of all elements entering substance), or a formula m=Vρ where V-substance volume, ρ - its density. In turn if necessary replace amount of substance with a formula n=V/Vm or you also find from the reaction equation.
4. Calculate a mass fraction of an element of complex substance by means of Mendeleyev's table. Put atomic masses of all elements entering substance if necessary multiplying on indexes. You receive the molar mass of substance. Find the molar mass of an element from Mendeleyev's table. Calculate a mass fraction, having divided the molar mass of an element into the molar mass of substance. Increase by 100%.