Advice 1: How to calculate percentage

The concept of the percentage content is used in chemistry, biochemistry, physics, food industry. This is one way to Express the concentration of the component in the total value. If a cent, hundredth of value, the percentage content shows the number of shares.
How to calculate percentage
You will need
  • - handle;
  • paper for records;
  • calculator.
If you need to calculate the volume percentage content of the substance x, use the formula: CV% = Vx*100/ Vобщ = Vx*100/(Vx+Vy+...+Vn), %;where Vx is the volume of the substance; Vобщ is the total volume, which is the sum of the volumes Vx, Vy,...Vn – component substances.
To calculate the mass percentage of substance x apply the formula:Cm% = Mx*100/Mobs = Mx*100/( Mx+My+...+Mn), %;where Mx – mass of the substance;Mobs is the total mass, which consists of mass Mx, My,...Mn – component substances.
If required to convert volume percentage content in mass, use the relationship: M = V*p, in kg; where M is the mass of matter, kg;V – volume, m3;p – density, kg/m3.
There are challenges to finding the percentage of a component resulting from mixing two solutions with different concentration.For example, you want to determine the mass percentage content of NaCl in solution obtained by mixing 1 liter of a 10% solution and 2 l of a 20% solution. Density of solutions of 1.07 g/cm3 and 1.15 g/cm3, respectively.
To solve find the mass of 1l of 10% solution and 2 l of 20% using the formula from step 3. Translate liters to cm3: 1l = 1000см3. You will receive at 1.07 kg and 2.30 kg. Fold both the masses and get a lot of mixed solution of 1.07+2,30 = 3.37 kg
Converting the formula from step 2, find the mass of NaCl in the first and second solution: Мсоли1 = 1,07*10/100 = 0,107 kg. Мсоли2 = 2,30*20/100 = 0,460 kg. Fold the masses and get a lot of salt in the resulting solution: 0,107+0,460 = 0,567 kg. By the formula from step 2, find the percentage content of salt in the mixture of solutions: 0,567*100/3,370 = 16,83 %.

Advice 2: How to calculate density

Density is one of the characteristics of matter, such as mass, volume, temperature, area. It is the ratio of mass to volume. The main task is to learn how to calculate this value and know what it depends on.
How to calculate density
The density of a substance is numerically the ratio of mass to volume of a substance. If you want to determine the density of a substance and you know its mass and volume, finding the density will not make you work. The easiest way to find the density in this case is p = m/V. It is measured in kg/m^3 in SI units. However, not always a given these two values, so you should know some ways by which you can calculate the density.
The density has different values depending on the type of substance. In addition, the density changes from salinity and temperature. With decreasing temperature, the density increases, and with the lowering of the degree of salinity decreases and the density. For example, the density of the red sea is still considered high, and in the Baltic sea it is already less. All of you have noticed that if the water to fuel, it POPs up. All this is due to the fact that oil has a lower density than water. Metals and stone substances, on the contrary sink because their density is higher. On the basis of the density of bodies there was a theory about their swimming.
Thanks to the theory of the swimming of bodies there was a formula that I can find the density of a body, knowing the density of water, the volume of the body and the volume of its immersed part. This formula has the form:Vпогруж. part / V of the body = p / p liq.It follows that the density of the body can be found as follows:R body = V submersible. parts * fluid R / V body.This condition is satisfied on the basis of the tabular data and the given volume V submersible. part V of the body.
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