Solution Stoichiometry - Titrations

A titration is an experimental technique used to determine the molarity of an unknown solution. When doing a titration, some special equipment is needed:

• Buret - contains the known solution, used to determine how much solution is added
• Stopcock - valve used to control the flow of solution from the buret
• Pipet - used to accurately determine volume of unknown solution
• Erlenmeyer Flask - container for unknown solution
• Indicator - used to identify the end point of titration
• Stock Solution - known solution

Example:

1. Jerome wants to determine the molarity of a Sodium Hydroxide sample so he does a titration with Hydrochloric Acid (HCl). He gathers the following data. 

Trial	1	2	3	4
Final Reading (mL)	13.3	26.0	38.8	13.4
Init. Reading (mL)	0.2	13.3	26.0	0.6
Volume Used (mL)	13.1	12.7	12.8	12.8

NaOH samples = 10.00mL          [HCl] = 0.75M   ( NaOH + HCl -> NaCl + HOH)

The first thing to do is to find the average volume used. Now, since trials 2,3 and 4 are relatively close to each other, we can exclude trial 1 in the averaging process. The average volume used is 12.8 mL. Now we used this in our conversion. 


0.0128L x 0.75mol x 1 x 1mol = 0.96M NaOH 
                     1L        1   0.010L

Buret and Stopcock

Erlenmeyer Flask
Pipet