pH Balance

pH Balance

The science behind ocean acidification is not as complicated as it may sound, but it will help to refresh your memory about the basic concepts of the pH scale and how it relates to the chemistry of the world's ocean.  Many people will forget this information as soon as they pass their chemistry exam, and will never think about pH again unless it relates to their fish tanks, swimming pools, or deodorant for women.  pH is a measurement of the amount of hydrogen ions in a solution, and the scale goes from 0 to 14.  pH values between 0 and 7 are considered acidic.  Values between 7 and 14 are basic.  A solution with a pH of 7 is considered neutral.  It is important to remember that being labeled an acid or a base is not a bad thing, many things that we consume regularly (like orange juice and soda) are acids.  What is important is that living things have adapted to cope with specific pH ranges, and the pH of ocean water is decreasing faster than many animals can adapt.

 

  • The pdf resource included in this lesson is a huge overview of ocean acidification and its effects on coral reefs.  For the purposes of this lesson: go over pages 11-14 for a brief explanation about ocean pH.
  • There is also a video of this same presentation with the speaker, Dr. Dwight Gledhill, discussing the science of ocean acidification.  The video is 30 minutes long, but you can watch the first six minutes of this talk to focus on the chemistry and science of ocean acidification.
  • For kinesthetic learners, check out the first lab activity from the "Ocean Acidification Lab Activities" pdf file.  The experiment is called Student Activity 1: Is Seawater More Like Lemons or Bleach?"  The pH testing activity can be done with students, staff, volunteers and visitors!
  • Stanford University's virtual urchin lab is a fun and easy way to refresh about acids, bases and the pH scale.  You can familiarize yourself with familiar acids and bases, and also see how ocean pH has changed since the industrial revolution.  http://virtualurchin.stanford.edu/AcidOcean/AcidOcean.htm
Lesson Take Away: 

Seawater is slightly basic on the pH scale, with a typical value of 8.1.  Ocean acidification means that in the year 2100, the water in the ocean is expected to move towards acidity, and may potentially reach a new pH of 7.8.  This may look like a small change, but on the pH scale, it is significant and will alter the ocean chemistry to which many species have adapted.

Last Updated: December 18, 2013
This is a lengthy pdf document of a powerpoint presentation that accompanies a talk by Dr. Dwight Gledhill with the Cooperative Institute of Marine and Atmospheric Science.  It is a good resource for background information about ocean acidification...

This is a lengthy pdf document of a powerpoint presentation that accompanies a talk by Dr. Dwight Gledhill with the Cooperative Institute of Marine and Atmospheric Science.  It is a good resource for background information about ocean acidification because it covers chemistry, carbon cycles, CO2 emmission, and focuses on the impacts of ocean acidification on coral reefs.  If you are looking to fully understand these concepts, check this out.

This pdf resource contains three fantastic classroom lab activities provided by the Ocean Acidification Subcommittee of the Ocean Carbon & Biogeochemistry Program.  The first activity is about the pH scale, and how to test solutions to determine...

This pdf resource contains three fantastic classroom lab activities provided by the Ocean Acidification Subcommittee of the Ocean Carbon & Biogeochemistry Program.  The first activity is about the pH scale, and how to test solutions to determine whether they are acids or bases.  The second activity simulates the chemical process of ocean acidification in a cup using human-generated carbon dioxide!  The third activity goes a step further and demonstrates the effects of ocean acidification on seashells using vinegar as the acid.