Question

Based on your endpoint indicated by the methyl orange and the equivalence points determined by the titration curve for your Na₂CO₃ titration using the pH electrode, which of the following are true? (Select all that apply.)

The methyl orange was not necessary since the pH change indicated the second equivalence point.

The methyl orange was not necessary since the pH change indicated the first equivalence point.

The endpoint and the second equivalence point occurred together.

The endpoint and the first equivalence point occurred together.

The methyl orange was necessary; otherwise the second equivalence point would have been missed.

The methyl orange changed color rapidly as the pH changed rapidly at the first equivalence point.

The methyl orange changed color rapidly as the pH changed rapidly at the second equivalence point.

Answer 1

1. The first end point is around pH=8-4 second end point in around pH = 4.0 methal orange works in the range pH 3.0 to 4.4 color change is yellow (basic) to Red (acidic ) A. As the second endroint falls in the working range of methyl orange, the indicator is caeful for detection of second endpoint only. when we use pH electrode for titration, the methyl orange indicator is not necessary because the pH vs volume of Hel Plot giver the both equivalence points. The true statements are ①, ② and ..