In a double indicator titration involving a mixture of and , the volume of HCl required to reach the — Redox Reactions and Volumetric Analysis Chemistry Question

💡 Solution & Explanation

Phenolphthalein changes color around pH 8-10. At this stage, all the strong base ( $NaOH$ ) is completely neutralized, but the weaker base $Na_2CO_3$ is only half-neutralized, converting into $NaHCO_3$ . Methyl orange is required to complete the neutralization down to $H_2CO_3$ .