A mixture of and required mL of using phenolphthalein. Another mL of the same was required to reach — Redox Reactions and Volumetric Analysis Chemistry Question
Question
A mixture of $NaOH$ and $Na_2CO_3$ required $25$ mL of $0.1 M$ $HCl$ using phenolphthalein. Another $10$ mL of the same $HCl$ was required to reach the methyl orange endpoint. The moles of $Na_2CO_3$ in the mixture are:
Answer: A
💡 Solution & Explanation
**Step 1:** In the second stage (from Ph to MeOH), only $HCO_3^-$ (formed from $Na_2CO_3$) is neutralized. <br>Meq $Na_2CO_3$ = Meq $HCl$ in 2nd stage = $10 \times 0.1 = 1$. <br>Moles $Na_2CO_3 = 1 / 1000 = 0.001$.
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