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Assertion: In the titration of Na(2)CO(3...

Assertion: In the titration of `Na_(2)CO_(3)` with `HCl` using methyl orange indicator, the volume of acid required is twice that of the acid required using phenolphthalein as indicaton.
Reason: Two moles of `HCl` are required for the complete neutralisation of one mole of `Na_(2)CO_(3)`.

A

If both the statements are TRUE and STATEMENT-2 is the correct explation of STATEMENT-1

B

If both the statements are TRUE AND STATEMENT-2 is NOT the correct explanation of STATEMENT-1

C

If STATEMENT-1 is TRUE and STATEMETN-2 is FLASE

D

If STATEMENT-1 is FLASE and STATEMENT-2 is TRUE

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question, we need to analyze both the assertion and the reason provided. ### Step 1: Understanding the Assertion The assertion states that in the titration of sodium carbonate (Na₂CO₃) with hydrochloric acid (HCl) using methyl orange as an indicator, the volume of acid required is twice that of the acid required when using phenolphthalein as an indicator. ### Step 2: Analyzing the Reaction with Phenolphthalein When phenolphthalein is used as an indicator, it changes color at a pH of around 8.2 to 10.0, indicating the endpoint of the titration when the solution is still basic. The reaction that occurs is: \[ \text{Na}_2\text{CO}_3 + \text{HCl} \rightarrow \text{NaHCO}_3 + \text{NaCl} \] In this reaction, sodium carbonate is only partially neutralized to sodium bicarbonate (NaHCO₃), which means that only 1 mole of HCl is required for every mole of Na₂CO₃ to reach this endpoint. ### Step 3: Analyzing the Reaction with Methyl Orange Methyl orange, on the other hand, changes color at a lower pH (around 3.1 to 4.4), indicating that the solution has become acidic. The complete neutralization reaction is: \[ \text{Na}_2\text{CO}_3 + 2 \text{HCl} \rightarrow 2 \text{NaCl} + \text{H}_2\text{O} + \text{CO}_2 \] Here, 2 moles of HCl are required to fully neutralize 1 mole of Na₂CO₃, resulting in the formation of sodium chloride, water, and carbon dioxide. ### Step 4: Conclusion on the Assertion Since the volume of HCl required when using methyl orange is indeed twice that required when using phenolphthalein, the assertion is correct. ### Step 5: Understanding the Reason The reason states that two moles of HCl are required for the complete neutralization of one mole of Na₂CO₃. This is also correct, as shown in the balanced equation for the complete reaction. ### Final Conclusion Both the assertion and the reason are correct, and the reason provides a correct explanation for the assertion. ### Summary of the Solution - **Assertion**: Correct - The volume of HCl required with methyl orange is twice that with phenolphthalein. - **Reason**: Correct - 2 moles of HCl are needed for complete neutralization of 1 mole of Na₂CO₃. - **Final Answer**: Both assertion and reason are true, and the reason is the correct explanation for the assertion.
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