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The basic chemistry equations you need for using a flame photometer

When using a flame photometer, you will eventually reach a stage where using mathematics is unavoidable. This handy guide should help you fix any issues which may arise, with information about the most basic needs in general chemistry equations for flame photometry.

The BWB XP Flame Photometer
The BWB XP Flame Photometer

How does concentration change with dilution?

In flame photometry, most of what you will be figuring out will come in either a liquid or solid form. Experts generally use a flame photometer to measure the concentration of ionic species in aqueous solutions. Often, you will need to change the concentration of a solution by changing the amount of solvent. Dilution is the addition of solvent, which decreases the concentration of the solute in the solution. Concentration is the removal of solvent, which increases the concentration of the solute in the solution.

How do I calculate dilution?

Mixing liquids together and altering concentrations can seem complex.

It’s easy to get overwhelmed if you do not have knowledge of this simple equation which can fix the issue. The formula for calculating a dilution is: C1 x V1 = C2 x V2. Broken down, this is where:

· C1 is the concentration of solution one

· V1 is the volume of solution one

· C2 is the concentration of solution two

· V2 is the volume of solution two

What this comes down to is the relationship between volume and concentration of mass.

Here, the units of volume and concentration must be given in the same form.

So, if the volume is in litres, the subsequent concentration must also be given in X per litre.

When calculating this, you will commonly need to divide by 1,000 to convert ml to litres.

When can I use this equation?

When a 1Mol/L sodium solution in a 10ml beaker is diluted to 0.1L, the equation for the final concentration of sodium is defined as follows:

· C1 = 1Mol/L

· V1 = 10ml

· C2 = Unknown

· V2 = 0.1L

As V1 is in the wrong form of unit for this calculation, it must be converted to litres to fit with the rest of the units:

· C1 x V1 / V2 x 1000 = C2

· 1 x 10 / 0.1 x 1000 = 0.10Mol/L

This is known as a 1:10 dilution – taking a single unit of solution and diluting it with 10x the amount of solvent, resulting in a 10x lower concentration of the solute.

How does this equation actually work?

It all comes down to the conservation of the mass diluted in the solution.

Concentrations are given in the units of mass per unit volume so, for every X much volume, there is X much mass. By multiplying the volume, we are only left with mass. What the equation actually states is that the mass diluted in the solution is constant over course of the dilution.


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