Hello Beyond Labz users!
We’ve recently had a few of our users understandably reach out to us in frustration about not being able to stop titrations with phenolphthalein indicator (or KMnO4) at the classic “light pink” color of the equivalence point. We have this feature request on our radar, but in the meantime, let me provide some details that will help you complete these experiments with a bit more precision and accuracy:
Our lab was written with introductory chemistry students in mind, so following a color change will get students typically within 2.5% (or less) of the correct volume of the equivalence point - you may notice our worksheets specifically say to look for a color change and not for the classic light pink color we see in these types of titrations.
However, if you would like to be a bit more analytical, our lab includes the pH and conductivity meters! If you go drop by drop through the equivalence point and graph the first derivative of the data (or use the jump in voltage for the KMnO4 titrations), the volume of titrant calculated will typically be within 0.1% or less of the correct value.
I hope this clears some things up and prevents some headaches for our titrations users until we can provide an update that will allow stopping points to be more precise. Thanks for using Beyond Labz and don’t hesitate to reach out with questions or concerns! We’re always looking for ways to improve our product, so we appreciate those who have reached out.