pH (using pOH and pKw)

pH^[1] is the measure of acidity of a solution. pH measurement is derived from the measure of hydronium ion concentration. Since the ion concentration is small in the solution, it is converted by the equation above to pH (the equation above is a derivation of a equation that can be found here) and compared against a scale. pH scale ranges from 0 to 14, 0 being acidic and 14 being basic.  At 25^oC the concentration of each ion (H⁺ and OH^-) is 1.0x10^-7(mol/L), when both of the concentrations remain equal then the solution becomes neutral, which is a pH of 7 on the scale.

Description

The equation is 

^[2]

where 

• pH is the acidity measurement (unit-less) 
• pOH is the measurement of basicity (unit-less)
• pK_w is the natural log of the water equilibrium constant, which is always 14 (to learn more about pK_w go here)

Related Topics

• pH from hydroxide ion concentration
• pH from hydronium ion concentration
• pH/pOH calculator

Supplement Material

• Khan Academy:
  • pH, pOH of strong acids and bases
  • Definition of pH
• HyperPhysics:
  • pH

References

[1]https://en.wikipedia.org/wiki/PH

[2]Whitten, et al. 10th Edition. Pp.713

[pH scale diagram]http://wiki.chemprime.chemeddl.org/index.php/PH_and_pOH_in_Everyday_Life