An air bubble is present in the stopcock at the start of the titration but is passed out during the titration. Would this error make your calculated molarity of zinc ions higher or lower than the true value?

Thanks!

I have no idea what you talking about BUT the volume of the buret will read too high so what effect will that have?

Ok, I got it, thanks Dr. Bob.

Passing out an air bubble during a titration can affect the accuracy of the calculated molarity of zinc ions. To understand how it would impact the calculated value, let's consider the titration process.

During a titration, a solution of known concentration (the titrant) is slowly added to a solution of unknown concentration (the analyte) until the reaction between the two is complete. At the endpoint, which is typically detected using an indicator or pH meter, the stoichiometric equivalence between the titrant and analyte is achieved, allowing for the determination of the unknown concentration.

In the given scenario, an air bubble is present in the stopcock at the start of the titration but is passed out during the titration. As the titration progresses, the air bubble may travel through the burette and affect the volume readings. If the volume of solution delivered is inaccurately measured due to the presence of the air bubble, it can impact the calculated molarity of zinc ions.

If the air bubble causes the delivered volume of titrant to be underestimated, i.e., less volume is measured due to the bubble occupying some space in the burette, the calculated molarity of zinc ions would be higher than the true value. This is because the calculated molarity is determined by dividing the moles of titrant used by the volume of titrant delivered. However, if a smaller volume of titrant is recorded due to the air bubble, the calculated molarity would be falsely higher.

On the other hand, if the air bubble causes the delivered volume of titrant to be overestimated, i.e., more volume is measured than the actual amount due to the bubble being displaced, the calculated molarity of zinc ions would be lower than the true value. This is because a larger volume of titrant would be recorded, resulting in a falsely lower calculated molarity.

Therefore, it is essential to carefully ensure that the titration apparatus is free from air bubbles to minimize errors in volume measurements and obtain accurate results.