Frequently Asked Questions
What is the relationship between pH and [H+]?
pH = -log10([H+]), and [H+] = 10^(-pH). A solution with [H+] = 1.0 x 10^-7 mol/L has pH = 7.00 (neutral at 25 degrees C). Each pH unit represents a 10-fold change in [H+]: pH 6 has 10x more H+ than pH 7; pH 4 has 1000x more H+ than pH 7.
What is pOH and how does it relate to pH?
pOH = -log10([OH-]). At 25 degrees C, pH + pOH = 14.00 (= pKw). So if pH = 11, then pOH = 3 and [OH-] = 10^(-3) = 0.001 mol/L. This relationship allows conversion between [H+] and [OH-] in any aqueous solution. At 37 degrees C (body temperature), pKw = 13.62, so neutral pH is 6.81, not 7.00.
Why does neutral pH change with temperature?
Neutral means [H+] = [OH-], which occurs at pH = pKw/2. The water dissociation constant Kw increases with temperature: at 0 degrees C Kw ~ 1.1 x 10^-15 (neutral pH = 7.47), at 25 degrees C Kw = 1.0 x 10^-14 (neutral pH = 7.00), at 50 degrees C Kw ~ 5.5 x 10^-14 (neutral pH = 6.63). A pH of 7.0 at 37 degrees C is actually slightly basic.
Provided by AllCalculators.io
Free online calculators for everyday. No registration required.
Estimates for informational purposes only.
Important Disclaimer: Estimates for informational purposes only.
This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.