**Arrhenius definitio**n and the commonly used

**pH scale**.

Objectives:

1. Define and give examples of Arrhenius acids and bases; classify a solution as neutral, acidic or basic, given the hydronium-ion or hydroxide-ion concentration.

2. Calculate the pH or pOH of a solution given the hydronium-ion or hydroxide-ion concentration.

3. Calculate the hydronium-ion or hydroxide-ion concentration given the pH or pOH.

Here is a brief overview (3+ minutes) of the Arrhenius definition of acids & bases:

This next video slows down to get into the math associated with pH and pOH:

Notice that he guides students through using their calculators to perform calculations with scientific notation -- I've included that in my lectures to students b/c they tend to enter "x 10" to a power versus using the

**EXP**or

**EE**buttons on the calculator, ending up with an answer higher by 1 power of 10 -- help your students avoid this!

Here are a few worksheets practicing pH/pOH problems:

http://chemistry.about.com/library/pdfs/acidbase.pdf

http://misterguch.brinkster.net/PRA027.pdf

I will be relating pH/pOH to Ka and Kb in my next post.

Check out

**my lab book "Chemistry on a Budget"**at amazon.com:

__http://www.amazon.com/Chemistry-Budget-Marjorie-R-Heesemann/dp/0578129159/ref=sr_1_1?s=books&ie=UTF8&qid=1389410170&sr=1-1&keywords=chemistry+on+a+budget__

Each lab is presented with

**two possible report formats**-- both labs use the same procedure page but each has a different conclusion page --

**one**with 10 questions to be answered as a conclusion,

**the other**with a full laboratory report required.

**This gives the teacher the option**of what type of report is desired!

I have a few links listed under

**Teaching Resources**that could be very useful -- if you haven't checked it out, the link is at the top of this page! I just added one that has several Powerpoint presentations that you might find useful.

***I'd love to hear from you!**Your feedback would really help me to focus on your needs. You might have had a school vacation around now are around this time) -- take advantage of the time and write me about your classroom experiences! There should be a "Contact" form below, or click on the "Contact" tab on the top right of this page.

Have a good week!