Statement 1: When a solution of Na₂CO₃ is titrated with HCl solution, the volume of acid solution required for the end point in case of methyl orange indicator is double than that required in case of

Question

Statement 1: When a solution of Na₂CO₃ is titrated with HCl solution, the volume of acid solution required for the end point in case of methyl orange indicator is double than that required in case of phenolphthalein indicator.

Statement 2: In case of phenolphthalein indicator, the sudden change in colour is observed when Na₂CO₃ is completely converted into H₂CO₃.

TestHub · Accepted Answer

I is correct: phenolphthalein shows its end point at half neutralization (Na₂CO₃ → NaHCO₃, 1 eq per mol), while methyl orange covers full neutralization (Na₂CO₃ → H₂CO₃, 2 eq per mol), so the methyl orange volume is double. II is incorrect: with phenolphthalein the colour change occurs at the NaHCO₃ stage, not at complete conversion to H₂CO₃. Hence (c).

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