Question

In the following reaction NaOH + S \(\rightarrow\) A + Na\(_2\)S + H\(_2\)O; A is

• A. Na\(_2\)SO\(_4\)
• B. Na\(_2\)SO\(_3\)
• C. Na\(_2\)S
• D. Na\(_2\)S\(_2\)O\(_3\)

Hint:

Sulfur disproportionates in hot alkali.

Answer 1

The Correct Option is B

To determine the correct product 'A' in the given chemical reaction, let's analyze the reaction step-by-step:

The reaction provided is:

\(NaOH + S \rightarrow A + Na_2S + H_2O\)

Given the options for 'A':

Na\(_2\)SO\(_4\)

Na\(_2\)SO\(_3\)

Na\(_2\)S

Na\(_2\)S\(_2\)O\(_3\)

The reaction involves sodium hydroxide (\(NaOH\)) reacting with sulfur (\(S\)). The product \(A\) must be formed alongside sodium sulfide (\(Na_2S\)) and water (\(H_2O\)).

Now, let's recognize the nature of the oxidizing process:

When sodium hydroxide reacts with sulfur, it can produce sodium sulfite (\(Na_2SO_3\)), which is a common product of such reactions. Sodium sulfite is a product when sulfur is oxidized in the presence of alkali:

- Sulfur is partly oxidized to sulfite anions (\(SO_3^{2-}\)), forming sodium sulfite (\(Na_2SO_3\)).

Therefore, the correct answer for 'A' is sodium sulfite (\(Na_2SO_3\)).

Let us examine why the other options are incorrect:

Na\(_2\)SO\(_4\)

• : Sodium sulfate is usually the oxidized product of sulfur in reactions with strong oxidizers or excessive oxidation conditions, which is not the case here.

Na\(_2\)S

• : Na\(_2\)S is a product of direct combination of sodium with sulfur without further oxidation ions such as sulfite.

Na\(_2\)S\(_2\)O\(_3\)

• : Sodium thiosulfate is another sulfur compound but forms under specific conditions, often involving a different set of reactants and sulfur compounds.

Hence, the correct answer is \(Na_2SO_3\).