Question

Please help me understand how to start this lab. I do not understand the wording. Thank you so much! :)

1. Create a buffer solution such that the pH=pKa, by adding half the amount of 1.00 M NaOH (prepared from the 6M NaOH provided in your kit) needed to reach the endpoint of 10 mL of vinegar.
   
   • This can be performed by titrating a 15.0 mL aliquot of vinegar with 1.00 M NaOH
     
   • Record the endpoint volume of NaOH
     
   • Add half the endpoint volume of NaOH to another 15.0 mL aliquot of vinegar into the test tube
     
   • The solution created in the previous step is a buffer solution such that the pH=pKa

Answer 1

Vinegar os mostly acetic acid. So, acetate buffere is going to be prepared. The buffer works best when acidic form and basic form are in equal proportions.

Therefore, [acetate] = [acetic acid]

This is gained when the titration is done half i.e., when the NaOH is added at a volume half of that is required for tge equivalence point. Because at the equivalence point all acetic acid molecules are converted to acetate. At half equivalence point acetate and acetic acid concentrations are the same. Taking 15 ml aliquote of the vinegar, firstly the equivalence point is measured and then it is calculated through proportion for 10 ml. Vinegar. A buffer solution takin half equivalence volume of NaOH is made for the 10 ml aliquote and tge 15 ml aliquote in the test tube. This is how the work is to start. Best. Hope it helps.