Common Mistakes

Calvin and Tull forgot to calibrate the pH sensor before beginning the titrations. As a result, their pH measurements were inaccurate. Even though the second equivalence point at 5.2 mL of HCl is close to the expected result, their data is unreliable.

After calibrating the pH sensor, Calvin and Tull's titration of nitric acid started just as they expected. However, instead of seeing an equivalence point at 5 mL of NaOH, they observed it at 5.8 mL. They realized they had incorrectly measured the initial volume of nitric acid.

A drop rate of 1 drop per 2 seconds or slower, allows time for each drop to be thoroughly mixed into solution and the pH sensor to respond.

Stirring the solution too quickly can cause it to splash outside the beaker, leading to inaccurate results.

Stirring too slowly does not allow the drops to be thoroughly mixed into solution before the pH measurement is recorded.