For definition of molar concentration of solution define amount of substance in moths which is in solution unit of volume. For this purpose find the weight and a chemical formula of the dissolved substance, find its quantity in moths and divide into solution volume.
It is required to you
- measured cylinder, scales, Mendeleyev's table.
Instruction
1. By means of exact scales find the mass of the dissolved substance in grams. Define its chemical formula. Then by means of Mendeleyev's table find atomic masses of all particles entering a molecule of initial substance and put them. If at a molecule there are several identical particles, multiply the atomic mass of one particle by their quantity. The received number will be to equally molar mass of this substance in grams on mol. Find amount of the dissolved substance in moths for what divide the mass of substance into its molar weight.
2. Dissolve substance in solvent. It can be water, alcohol, air or other liquid. Track that in solution there is no firm particle of substance left. Fill in solution in a measured cylinder and find its volume by the number of divisions on a scale. Measure volume in cm³ or milliliters. For definition of directly molar concentration divide amount of the dissolved substance in moths, into solution volume in cm³. The result will turn out in moths on cm³.
3. If solution is already ready, then in most cases its concentration is defined in mass fractions. For definition of molar concentration calculate the mass of the dissolved substance. On scales determine the mass of solution. Increase the known percent of the dissolved substance by the mass of solution and divide into 100%. For example, if it is known that there are 10% solution of table salt, it is necessary to increase the mass of solution by 10 and to divide into 100.
4. Define a chemical form of the dissolved substance and by means of already described technique find its molar weight. Then find amount of the dissolved substance in moths, having divided the calculated weight into molar. By means of a measured cylinder find the volume of all solution and divide amount of substance in moths into this volume. Molar concentration of substance in this solution will be result.