Chemistry Forum

Explain whether the following techniques errors would result in a high or a low experimental determination of the molar concentration of CH₃COOH in vinegar.
1) A student uses the pipet bulb to blow the last bit of vinegar sample from the tip into the titration flask, after the pipet was drained.

2) A student fails to clean the pipet first. After delivering the vinegar sample, the student notices a drop of vinegar clinging to the inner surface of the pipet.

3) A student stops the titration when the pink persists throughout the solution for less than 10 s.

4) After completing a titration, a student notices that the buret is not clean. Droplets of NaOH solution are clinging to the inner surface of the buret.

tanya06 wrote:Explain whether the following techniques errors would result in a high or a low experimental determination of the molar concentration of CH₃COOH in vinegar.
1) A student uses the pipet bulb to blow the last bit of vinegar sample from the tip into the titration flask, after the pipet was drained.

higher, more than an aliquot has been titrated

tanya06 wrote: 2) A student fails to clean the pipet first. After delivering the vinegar sample, the student notices a drop of vinegar clinging to the inner surface of the pipet.

lower, less than an aliquot has been titrated

tanya06 wrote: 3) A student stops the titration when the pink persists throughout the solution for less than 10 s.

lower, not all acid was titrated

tanya06 wrote: 4) After completing a titration, a student notices that the buret is not clean. Droplets of NaOH solution are clinging to the inner surface of the buret.

higher, because NaOH which stuck on the inner surface will be counted as spent for titration