you need
  • - scales;
  • - ability to make and convert proportions.
Guide
1
With scales measure weight substance, mass fraction of one of the elements is known.Since all the substance of a given mass is taken as 100%, make a proportion of finding the ratio of the mass fraction of a percentage of 100%, and to equate it with respect to the ratio of the mass element and the whole matter.Transforming a formula that will get the value of the mass of the element mixture or alloy.The mass will be equal to the product of the mass fraction of the element in the mass of all matter, divided by 100 m0 = (M • ω%) / 100% .For example, if you know that in the bronze ingot weighing 4 kg mass proportion of copper is 80%the mass of pure copper is equa
l to m0 = (4 kg • 80%) / 100%.When calculating the value will get 3.2 kg.
2
In that case, if the mixture or alloy composed of many substances and known mass share of each of them, get their mass .For this to apply the calculation of each substance listed in the previous paragraph.Before calculating, always make sure that all the mass fraction of substances add up to 100%, otherwise the payment will neveren.Posle how the calculation is made, and the mass of substances are found, make sure that the total mass of all substances is the mass of the starting material.For example, 160 g of the solution contained 10% sulfuric acid, 5% nitric acid and 85% water.The weight of sulfuric acid was m0 = (160g • 10%) / 100% = 16 g, the mass of nitric acid m0 = (160 g • 5%) / 100% = 8g and the water mass m0 = (160 kg • 85%) / 100% = 136, with the check will be received: 16 + 8 + 136 = 160g.
3
If you know the weight of one of the elements, and the mass fraction of , is not weighing the matter, determine its mass .The weight of all the matter corresponds to 100% of the mass fraction.Then, making the proportion of shares equating to a ratio of the mass ratio of the corresponding mass.Rasschitayte mass of all matter by multiplying the mass his part to 100% and dividing its mass fraction of a percentage M = (m0 • 100%) / ω%.For example, if you know that for a 10% solution of sodium chloride in water was added to 12 g of the substance, the weight of the total solution will be M = (12 • 100%) / 10% = 120 g