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Texas ISD School Guide
Texas ISD School Guide







Short Stories for Teachers

Acids and Bases - The Basics of Using the PH Scale
By:Elizabeth Blake

The pH scale is a way to describe acids and bases. It reaches from 0 to 14.

Substances that test from 0 up to 7 on the pH scale are called ACIDS. They are acidic in nature. Examples are lemon juice and vinegar. The number 7 is NEUTRAL. Above 7 up to 14 are called BASES and are basic in nature. Examples are baking soda and also bleach.

An easy way to remember this is that the words ACID and BASE are in alphabetical order. Therefore, ACIDS come first on the scale. Another word for BASE is ALKALINE. Fortunately for us, the words ACID and ALKALINE are also in alphabetical order, so it's easy to remember.

The closer to 0 a substance is, the stronger an acid it is. The closer to 14 a substance is, the stronger a base it is. Substances that are too close to 0 or 14 are dangerous or caustic and must be handled with safety measures in mind. Battery acid is very low on the scale, therefore being very ACIDIC. Lye is very high on the scale and therefore very BASIC and dangerously caustic. ACIDS and BASES neutralize each other.

The term "pH" refers to the "power of the Hydrogen ion." It's calculated using logarithms and is an expression of the concentration of dissolved Hydrogen ions in solution.

We can determine if a substance is ACIDIC or ALKALINE (BASIC) by using an INDICATOR. An INDICATOR indicates if a substance is an ACID or a BASE. INDICATORS are found in nature. One example of an INDICATOR is red cabbage juice. To make this, simply boil up some cabbage leaves in water and let the solution seep. After it's cooled, you can take some and add a few drops to a vinegar/water solution. It should turn pink, indicating that the vinegar is an ACID.

Then, add some of your INDICATOR solution to a baking soda/water solution. It should turn green, indicating that the baking soda is BASIC (ALKALINE.)

Solutions that are NEUTRAL will not change the color of the cabbage juice, such as distilled water. Try some safe household products (example, sugar water, orange juice, Milk of Magnesia) and see what you get.

A doctor may order a test of your arterial blood to see if your blood is the proper pH. Your blood ideally should be between pH 7.38 and 7.42.

You can use LITMUS PAPER to find a more precise reading of the pH of the substance you are testing, not just whether it's an ACID or a BASE. Also, if you have a swimming pool in your backyard, you must buy pH paper to test the pool water to make sure it's the proper pH. Pool water should be between pH 7 and 8. If the pH gets too high, you must add some ACID to bring the pH back down into the good range. But too much acid, and you won't be able to swim in your pool!

Always use safety precautions such as safety glasses when working with ACIDS and BASES.

After working 20 years as an ASCP certified Med Tech, I switched careers to teach science in an inner-city high school. I've written a memoir about the joys of teaching and the obstacles I fought. No Child Left Behind? The True Story of a Teacher's Quest by Elizabeth Blake on http://www.BarnesandNoble.com and Amazon. Drugs, gangs, a riot, shootings, murdered students, abusive principals - all contributed to the stress which eventually drove me from the students I loved.

The book celebrates triumph over adversity. To read the first page, visit http://www.elizabethblakeonline.com






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