To understand the complexity and sensitivity of pH altering, consider the following example: calculate the change in pH of reverse osmosis water from 7 to 8.

First some information is needed about the system. A strong base is used to increase the pH, Remix pH Up, also known as potassum hydroxide. The density can be found based on the percent range given on the SDS sheet. The molar mass is also needed to correlate the physical mass to the molecular scale, which is what the chemicals operate on.

Dividing the density by the molecular mass and multiplying by the mass percent of the pH Up solution will give the overall molar concentration (molarity) of the starting solution.

Next, choose how much of the pH Up to add, 1 mL will be sufficient. Divide the molarity value by the amount of milliliters added and that gives the amount of substance added to the system.

Now, how much water can be adjusted? Let's see what happens when we add 1 mL of pH Up to 1 gallon of water. Divide the molar amount of substance added by the volume of water. One gallon of water is 3.785 L or 3785 mL.

This gives the molar concentration of hydroxide ions in the solution. However, pH is measured from the concentration of hydronium ions in solution. pH and pOH summed together equal 14, so a quick rearrangement gives the pH as 8.2.

What is the significance of this? Finding this result means that for almost every 1 gram of strong base in Remix Chem pH Up, it changes the pH of almost 4 liters of water by one level. This is due to the nature of acidity being logarithmic, meaning that each number on the pH scale is different by a factor of 10.

This example only works under ideal conditions. 25oC and no other dissolved solids of any kind to interfere with the dissociation equilibrium. There are many other variables to consider. For instance, as the temperature of the water increases, the solution will read at a lower pH meaning more acidic. These factors among the task of accurately adding such a small amount of pH adjuster shows how difficult it is to add the right amount.

If you need help with adjusting your pH, please contact us at chemist@remixchem.com

- Greg Arias

Head Chemist

Remix Chem