Question

Assertion :In the titration of $N{a}_{2}C{O}_3$ with $HCl$ using methyl orange indicator, the volume required at the equivalence point is twice that of the acid required using phenolphthalein indicator. Reason: Two moles of $HCl$ is required for the complete neutralization of $1$ mole of $N{a}_{2}C{O}_3$.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

$N{a}_{2}C{O}_3+HCl\to NaHC{O}_3+NaCl$
At this point of the reaction when $NaHC{O}_3$ is formed, phenolphthalein changes colour but when methyl orange is used as an indicator, it changes colour when complete reaction takes place.
$N{a}_{2}C{O}_3+2HCl\to 2NaCl+C{O}_2+H_{2}O$