Guide

1

easiest option determine the concentration of interest - when you know the initial mass of dry matter, subsequently dissolved.Assume initially had 15 grams of some salts.Then it is completely dissolved in water.We need to calculate the percentage concentration

**.** 2

first weigh the container with a solution.For example, you will have 800 grams.Then pour the solution and weigh the empty container.Suppose it weighs 550 grams.A further object is simple: 15 / (800 - 550) = 0.06, or 6%.Here is the concentration of the solution

**.** 3

little complicate the task.Take 20 grams of salt (sodium chloride), and dissolve it in a certain amount of water.Then, the overflow solution in a graduated cylinder and carefully add water, bring the volume to 200 milliliters.Wha
t is the percentage concentration of the resulting solution

**?** 4

It would seem that the task - simply nowhere.The density of water is one, therefore, 200 ml - 200 grams, and the percentage concentration will be 20/200 = 0.1, or 10%.But do not rush to conclusions.After all, you do not have 200 milliliters of pure water and 200 milliliters of solution

**, the density of which is different from the unit.** 5

So you, as in the above case, it is necessary to know the total weight of the solution

**M, initially weighing vessel with him, and then - an empty vessel.Then, section 20 (a lot of salt) on M, and multiplying the result by 100%, you will get the answer.** 6

Well, if you for some reason it is not possible either to weigh or measure the amount?How, then, to determine the concentration of interest

**solution**?For example, there is a certain amount of water**solution of sulfuric acid - a well-known substance.Before you set a goal - to calculate its interest****concentration**, without using any weights or measuring utensils. 7

At first glance, a very difficult task.And in fact, solve it - a piece of cake.The fact is that almost any substance which is used in various industries, there are so-called "table of densities

**solution**ยป.But sulfuric acid - the substance is so widely used that to find a table for it is not difficult.It is the most reference books on chemistry. 8

First of all, you need to measure the density of sulfuric acid with a device called "densitometer" (in other words it can be called "densitometer").Suppose the obtained value is equal to 1.303 gram / milliliter.In the table, determine the density: a solution which corresponds to the percentage concentration of this value.This 40% solution of sulfuric acid.The problem is solved.