Question

$\textbf{A and B formed in the following reactions are:}$ \[ \text{CrO}_2\text{Cl}_2 + 4\text{NaOH} \rightarrow \text{A} + 2\text{NaCl} + 2\text{H}_2\text{O} \] \[ \text{A} + 2\text{HCl} + 2\text{H}_2\text{O}_2 \rightarrow \text{B} + 3\text{H}_2\text{O} \]

• A. $\text{A} = \text{Na}_2\text{CrO}_4, \, \text{B} = \text{CrO}_3 \\$
• B. $\text{A} = \text{Na}_2\text{Cr}_2\text{O}_4, \, \text{B} = \text{CrO}_4 \\$
• C. $\text{A} = \text{Na}_2\text{Cr}_2\text{O}_7, \, \text{B} = \text{CrO}_3 \\$
• D. $\text{A} = \text{Na}_2\text{Cr}_2\text{O}_7, \, \text{B} = \text{CrO}_5 \\$

Answer 1

The Correct Option is A

To analyze the reactions, we need to identify the products formed in each step.

First Reaction: The reaction of dichromate with sodium hydroxide produces sodium chromate:

Cr₂O₇²⁻ + 4NaOH → 2Na₂CrO₄ + 2H₂O

The product formed in this reaction is Na₂CrO₄.

Second Reaction: The sodium chromate reacts with chlorine gas and water. The products typically involve the formation of chromium trioxide:

A + 2Cl₂ + 2H₂O → B + 3H₂O

Here, B is identified as CrO₃ (chromium trioxide) when considering oxidation reactions of chromium compounds.

Thus, the correct identification of products A and B leads to: A = Na₂CrO₄, B = CrO₃

Answer 2

Let's analyze the given reaction step by step to identify the compounds \(\text{A}\) and \(\text{B}\).

The first reaction given is:

1. \(\text{CrO}_2\text{Cl}_2 + 4\text{NaOH} \rightarrow \text{A} + 2\text{NaCl} + 2\text{H}_2\text{O}\)

In this reaction, chromyl chloride (\(\text{CrO}_2\text{Cl}_2\)) reacts with sodium hydroxide (\(\text{NaOH}\)), producing sodium chromate (\(\text{Na}_2\text{CrO}_4\)), sodium chloride (\(\text{NaCl}\)), and water (\(\text{H}_2\text{O}\)).

The intermediate compound, therefore, is \(\text{A} = \text{Na}_2\text{CrO}_4\)

The second reaction transforms this intermediate:

1. \(\text{Na}_2\text{CrO}_4 + 2\text{HCl} + 2\text{H}_2\text{O}_2 \rightarrow \text{B} + 3\text{H}_2\text{O}\)

In this case, sodium chromate reacts with hydrochloric acid (\(\text{HCl}\)) and hydrogen peroxide (\(\text{H}_2\text{O}_2\)) to form chromium trioxide (\(\text{CrO}_3\)) and water.

Therefore, \(\text{B} = \text{CrO}_3\)

Looking at the options provided, the correct answer is:

\(\text{A} = \text{Na}_2\text{CrO}_4, \, \text{B} = \text{CrO}_3\)

This reasoning follows each reaction's requirement, leaving us with the final identification of the chemical compounds. Thus, the solution is consistent with the given reactions.