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Molarity

Molarity

Author: Jose Popoff
Description:

1. Express the concentration of a solution in terms of molarity.

2. Define dilutions.

3. Given the amount (expressed as volume) and concentration of a solution, determine the volume of solvent required to perform a dilution at any given concentration.

4. Prepare a determined volume of a diluted solution from a stock concentrated solution.

A very common expression used by scientists to express the concentration of a solutions is Molarity (Mor molar concentration.

The molar concentration relates the number of moles of the solute with the Liters of solution.  

For example, in order to prepare a 1.00 M aqueous (dissolved in water) solution of salt (sodium chloride), 1 mol of salt is dissolved in enough water to prepare 1 liter of solution.

Sometimes scientist need to dilute certain stock solution of acids.  Stock solutions are concentrated solutions of substances.  When the lab buys a bottle of acid, they buy the stock solution.  Dilution is necessary to perform certain experiments.  When you dilute a solution, you are merely decreasing its concentration.  

To prepare a given volume of a diluted solution you need to know what amount of the concentrated stock solution you will need.  Mathematically, the product of the concentration and volume of stock solution must always be the same as that of a diluted solution.  Expressed as an equation:

 

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Tutorial

Example 1

Example 2

Example 3