pH, pOH calculations Titration Calculations Chemistry 5/29/15

Drill l Drano is mainly sodium hydroxide. The [OH-] is often around 0.35 M. l Calculate the pH, pOH, and [H+] l HW: Finish Acids and Bases Review #35-37 (I’ll check the whole thing on Monday)

Objectives IWBAT: Calculate the pH and pOH of a solution using pH scale calculations Calculate the concentration of an unknown acid by using titration l NOTES: Titration Lab–6/2 & 6/3—Tuesday and Wednesday – CLOSED TOE SHOES Acids & Bases Test – Friday 6/5

Titration Notes/Demo

Titration l An acid-base titration is a carefully controlled neutralization reaction: Acid + Base  Salt + Water ex. HCl (aq) + NaOH (aq)  NaCl (aq) + H 2 O(l) l The point of titration is to determine the concentration of an unknown acid or base, using a standard solution that has a known concentration.

Goal of Titration l Procedure used to determine the concentration of an unknown acid or base l Standard solution – solution with the known concentration

More about Titration l The equivalence point is when all of the acid and base have neutralized each other. l The end point is when the indicator changes color. l They should be close together – Why? l Some indicators change at high pH, some at low pH.

Titration l We will be using phenolphthalein as our indicator. l What color is it? l Ms. Bloedorn will demonstrate.

Equivalence Point l Use phenolphthalein as an indicator Turns fuchsia in a basic solution Stop titrating when the solution turns light pink This is called the endpoint

Titration Calculations l Let’s go through Scenario #1 together. l Do Scenario #2 on your own. l Let’s review

Titration Practice Problems l Work on the Titration Problems l Make sure to show the mole ratio step! l I’ll circulate to help—check the answer key as you go

Closure l What is the point of a titration? l What is the difference between “end point” and “equivalence point”?