To calculate parts per million (ppm), divide the mass of the solute by the mass of the solution and multiply by 10^6. This represents the concentration in terms of mass per million parts of the solution.
To find the parts per million (ppm) of a substance, you need to understand that ppm is a way of expressing very dilute concentrations of substances.
One part per million (ppm) represents 1 part of the substance in 1 million parts of the total solution, which is often equivalent to one milligram of substance per liter of solution (mg/L).
The formula to calculate ppm is:
ppm = (mass of solute / mass of solution) × 10^6
Here's how you do it step-by-step:
Measure the mass of the solute (the substance you're interested in).
Measure the total mass of the solution (solute plus solvent).
Divide the mass of the solute by the total mass of the solution.
Multiply the result by 10^6.
For example, if you have 2 mg of salt dissolved in 1 kg of water:
ppm = (2 mg / 1,000,000 mg) × 10^6 = 2 ppm