pH of Water Definitions and Explanation

From pH 0 to pH 7,solutions are acid.
From pH 7 to pH 14, solutions are alkaline.

The activity of hydrogen ions can be most conveniently expressed in logarithmic units and the abbreviation “pH” is designated to represent the negative base 10 log of the hydrogen ion activity in moles per liter.

The pH may be expressed mathematically as follows pH = Log 1/[H+] where the H+ is the amount of hydrogen ions in solution in moles per liter.

Pure water is itself disassociated to a slight extent into the species H+ and OH-. This disassociation may be written as [H20] = [H+] + [OH-].

The equilibrium for this equation can be expressed as [H+][OH-]/[H20] = Kw. By convention, the activity of the liquid water is taken to be unity in this very dilute solution and the constant KW is then equal to the product of the activities of [H+] and [OH-]. This ion activity product for water at 25° C. is in exponential terms 10-14.000 .

The two place log of Kw is -14.00. By definition, the [H+] = [OH-] at neutrality and therefore pH = 7.

At higher temperatures, Kw increases, and the neutral value for pH becomes smaller. For instance, the neutral value pH at 30° C is 6.92. when there is an increase in the concentration of [H+] ions, a 7 resultant lowering of the pH value is observed. Conversely, a reduction in the [H+] concentration brings about a higher pH value.

From this relationship a pH scale has been devised. This scale ranges from 0 corresponding to an acidic solution with the hydrogen ion concentration equal to 1 through pH 7. The pH 7 is considered neutral. From neutrality to pH 14, the scale corresponds to a basic solution.

Next Topics…
Significance of pH of Water
Return to pH of Water

Comments are closed

...more from Dr. Gordon Snyder
Dr. Gordon Snyder on Google


info@sciencefaircenter.com

Home | Privacy Policy | Customer Service | Contact Us | Links

Visa Master Card AmEx PayPal

Please visit our family of websites

Student water science projects
SchoolScienceKits.com
ScienceFairCenter.com
ScienceFairWater.com
ScienceFairCenter.com online store
SchoolScienceKits.com/environmental online store
SchoolScienceKits.com/drinking online store
Watercenter.org

Whales Without Borders
WhalesWithoutBorders.info

Water filters, water test kits, water equipment
Watercenter.com
Watercenterfilters.com
Watercenter.net

New Water Sciences Websites
Basic Water Science Topics
Student Water Kits
Photos, Videos No Fence Wetland Restoration

Scrapbook card making paper crafts
Urbanscrapbooker.com
Urbanscrapbooker.com online store
ScrappysNeighborhoodDesigns.com
Urban Paper Crafter Store Map
Urban Paper Crafter Videos

Music, music composition, restore vinyl records
BarrySebastian.com
SebastionAndTheDeepBlue.com
Cleanlp.com
Cleanlps.com online store
JonesTechServices.com
spam prevention


All our websites are different...
Website created by Gordon Snyder and hosted by: synergos.com
Last updated on:

Family Friendly Website Safe Surf Sites Water Friendly Website Award Internet Rating Content Assoc.
www.sciencefairwater.com © 1998 - 2020 Gordon Snyder & Consultants, Inc., All rights reserved .