Putting Your Spreadsheet to Work

In Sections 10-1 to 10-3, we calculated titration curves because they helped us understand the chemistry behind a titration curve. Now we will see how a spreadsheet decreases the agony and mistakes of titration calculations. First we must derive equations relating pH to volume of titrant for use in the spreadsheet. 

The charge balance states that, in any solution, the sum of positive charges must equal the sum of negative charges, because the solution must have zero net charge. For a solution of the weak acid HA plus NaOH, the charge balance is 

Titrating a Weak Acid with a Strong Base 

Consider the titration of a volume of acid HA (initial concentration C ) with a volume Vb of NaOH of concentration Q. The concentration of Na is just the moles of NaOH (CbVb) divided by the total volume of solution (Va + Vb)  

Substituting for [Na ] (Equation 10-9) and [A ] (Equation 10-13) in the charge balance (Equation 10-8) gives 

---