Student X titrated 25 cm\(^{3}\) of Na\(_{2}\)CO\(^{3}\) with 0.1 mol dm\(^{-3}\) HCI, using methyl orange as indicator. Student Y carried out the same exercise but used phenolphthalein as an indicator. Which of the following statements about the titration is true?
hydrogen chloride gas was released in the reactions in both titrations
the titer values obtained from the titration are equal
the titer value obtained by X is twice that of Y
the titer value obtained by Y is twice that of X
Explanation
Video Explanation
No video available
Post your Contribution
Discussions (6)
Student X titrated 25 cm3 of Na2CO3 with 0.1 mol dm−3 HCI, using methyl orange as indicator. Student Y carried out the same exercise but used phenolphthalein as an indicator. Which of the following statements about the titration is true?
A. hydrogen chloride gas was released in the reactions in both titrations
B. the titre values obtained from the titration are equal
C. the titre value obtained by X is twice that of Y
D. the titre value obtained by Y is twice that of X
The appropriate indicator to use depends on the titration. Methyl orange changes color at a pH around 4 while phenolphthalein does so at a pH around 8. Therefore, if you were titrating a strong acid with a weak base, then you would use methyl orange; and if you were titrating a weak acid with a strong base, phenolphthalein would be more appropriate than methyl orange. Therefore in X where methyl orange(pH 4) is used, more acid is required to bring the pH of the solution to 4.
But in Y little acid would be required to bring the solution to pH of 8.
In the titration of Na2CO3 with HCl using methyl orange indicator, the volume required at the equivalence point is twice that of the acid required using phenolphthalein indicator 1. This is because two moles of HCl are required for the complete neutralization of one mole of Na2CO3 1. So, in this case, C. the titer value obtained by X is twice that of Y is true.
