Solutions - Definition, Molarity, Unit Conversion Flow Chart, and an Example

Greetings,

This post will discuss the most common composition unit of solutions used by chemists, molarity. This post will discuss the most common composition unit of #solutions used by chemists, #molarity.

A solution is a homogeneous mixture in which one or more parts are dispersed through a "main" component of the mixture.  Technically, solutions are found as all three states of matter.  The chemist works with liquid state solutions, primarily.

First, a little background information on solutions.  A solution consists of one or more solutes dissolved in or dispersed through the solvent, the main component.  A chemist works with solutions, often, and the science of chemistry provides a standard method for preparing solutions; once again, molarity.  Molarity is defined as the number of moles of solute contained in one liter of solution.

The #molar mass of the solute (usually a compound) is utilized to prepare a solution with a certain molarity.  The chemist needs three pieces of information to properly prepare a molar concentration solution: 1) the desired volume of solution, 2) the desired molarity concentration, and 3) the molar mass of the solute.  The relationships between the three pieces of information just mentioned are provided in the diagram, below.

Here is an example.
A chemist needs to make 1500 mL of a sodium chloride (NaCl) solution with a molarity of 2.00 mol/L (2.00 M).  What mass of solid sodium chloride solute is needed?

We'll need the molar mass of sodium chloride: molar mass Na + molar mass Cl
Upon referencing the periodic table, molar mass NaCl = 22.99 g/mol + 35.45 g/mol = 58.44 g/mol
Here is the rest of the calculation:

So, a chemist can weigh out approx. 175.32 grams of sodium chloride and dissolve in sufficient water to make 1500 mL solution with a concentration of 2.00 mol/L.

That's it for this post!
I'll be back with another, soon!