Why is methyl orange not suitable indicator for h2c2o4 and naoh

M.O. changes color approx 4 (a little < 4.0) and H2C2O4 and NaoH don't change at that point.

Methyl orange is an acid-base indicator that changes its color based on the pH of the solution. It turns red in acidic solutions and yellow in basic solutions. While it is commonly used in many acid-base titrations, it is not suitable for titrations involving oxalic acid (H2C2O4) and sodium hydroxide (NaOH) due to a couple of reasons.

Firstly, the pH range at which methyl orange changes color is not compatible with the pH range of the titration between oxalic acid and sodium hydroxide. Methyl orange changes color at a pH range of approximately 3.2 to 4.4, which is more suitable for strong acid-strong base titrations. In the case of oxalic acid and sodium hydroxide, the pH at the equivalence point is around 8, which is outside the range of methyl orange's color change. As a result, it would not provide a clear and distinct color change at the endpoint of the titration.

Secondly, using methyl orange as an indicator for this specific titration can lead to inaccurate results. Oxalic acid is a strong reducing agent, and it can reduce the methyl orange indicator, causing a premature color change. This unexpected color change can make it difficult to determine the exact endpoint of the titration accurately.

To find a suitable indicator for the titration between oxalic acid and sodium hydroxide, you can choose an indicator with a pH range that covers the pH of the equivalence point of the titration, which is around 8. One suitable indicator for this titration is phenolphthalein, which changes its color from colorless to pink in a pH range of 8.2 to 10. In this case, phenolphthalein would provide a clear and distinct color change at the endpoint of the titration and help ensure accurate results.