A mixture of 0.84 g of NaHCO 3 , 4.0 g of NaOH and 10.6 g of Na 2 CO 3 is dissolved in 100 ml H 2 O . The solution obtained is thus titrated with 0.5 M HCl solution. Which of the following opt

Question

A mixture of 0.84 g of NaHCO 3 ​ , 4.0 g of NaOH and 10.6 g of Na 2 ​ CO 3 ​ is dissolved in 100 ml H 2 ​ O . The solution obtained is thus titrated with 0.5 M HCl solution. Which of the following option is correct?

TestHub · Accepted Answer

At the phenolphthalein endpoint, NaOH is completely neutralized, and Na₂CO₃ is partially neutralized. Milliequivalents of NaOH + milliequivalents of Na₂CO₃ = $(\frac{4}{40} + \frac{10.6}{106}) \times 1000 = 20$ . Milliequivalents of HCl required = 20.

Therefore, the volume of HCl required = $\frac{20}{0.5} = 400$ ml.

At the methyl orange endpoint, all three will be completely neutralized.

Milliequivalents of NaOH + Na₂CO₃ + NaHCO₃ = $(\frac{4}{40} + \frac{2 \times 106}{106} + \frac{0.84}{84}) \times 1000 = 310$ . Milliequivalents of HCl required = 31.

Volume of HCl required = $\frac{31}{0.5} = 620$ ml.

Therefore, the volume of HCl required at the methyl orange endpoint after the phenolphthalein endpoint = $620 - 400 = 220$ ml.

Chemistry - Ionic Equilibrium Question with Solution | TestHub

Options:(select one or more)

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