Adv. Chem - 11/17 - pH, My First Titration Lab Report

I.  Arrhenius said that an acid contains an H+.  Also, a  base contains an OH-.  Looking at what you see above, often abbreviated as H2O --> H+  +  OH-  , water, all on it's own, donates its own H+ and OH-.  Therefore, it acts as both an acid AND a base.  This is called AMPHOTERIC.

Also, notice that this is a "double arrow" reaction.  That means it is like a teeter totter.  It flows back and forth (as needed).

pH is the measurement of the concentration of H+ (acid) in a solution.  Before we get to that, though...scientific notation.

II.  Let's figure out how to use YOUR calculator to switch between traditional and scientific notation.  Also, note that scientists use "E" (or "e") rather than x10^x.  This infuriates math folks, but it's what we do. It literally stand for "the exponent of ten in scientific notation." Some calculators (old school) have a button EE, which means "enter exponent."

III.  pH and the logarithmic scale.  Use Legos to build towers that are 

• 1e0 tall

• 1e1 tall

• 1e2 tall

The change you see from one to the next to the next is what you see when you move from one pH value to another to another.  It is NON-LINEAR.  It is logarithmic.  

IV. My First Titration lab report. 

Is your reaction written?

Do you have labels and units with all data?

Do all calculations have a description - what are you determining by doing the calculation?

You did three trials. Should we report all three? 

What are possible sources of error?

IV.  So, let's calculate the pH of the following solutions:

• 0.000010M HCl

• 0.00100M HCl

• 0.1M HCl

• 1.00M HCl

• 10.00M HCl

Let's do it in reverse.  What is [HCl] of the following solutions:

• pH = 2.67

• pH = 1.0

• pH = 12.995

V.  Back to water.  What is the [H+] of water (neutral)?  What is [OH-]?