Friday 19 September 2014

Sketching Titration Curves

These look daunting, but it isn't actually very hard to get the general shape correct. We used a weak acid vs. strong base example:




Thursday 18 September 2014

Titration Curves - Introduction

This was a whirlwind introduction to Titration Curves. Tomorrow, we will look at the calculations to determine the initial and final pH. Next term, we will look at how to calculate equivalence point volume and pH, and in the buffer region.




Tuesday 16 September 2014

pH of Weak Acids

This is a very difficult concept. Every student should be able to write a hydrolysis equation, base dissociation expression (KB), and calculate KB from pKA or KA (provided in the question). Beyond that, it will take a lot of practice:






Thursday 11 September 2014

Weak Acids

It is a bit trickier to calculate the pH of a weak acid. This is because they only partially dissociate. However, this means that these acids have an equilibrium constant (called the acid dissociation constant), which can be used to calculate the hydronium ion concentration:


The process for doing this is:
  1. Write the balanced equation for the dissociation with water.
  2. Write the acid dissociation expression.
  3. Substitute and solve
    • [hydronium] = [conjugate base] = x
    • [acid] = original concentration stated in the question (only partially dissociated)
  4. Calculate pH