Question

The sol formed in the following unbalanced equation is:
\[ As_2O_3 + H_2S \rightarrow {?} \]

• A. As$_2$S$_2$
• B. As$_2$S$_3$
• C. As
• D. S

Hint:

Colloidal sols can form from precipitation reactions involving metal oxides and hydrogen sulfide.

Answer 1

The Correct Option is B

Step 1: Identify the Reaction Type 
The reaction involves arsenic(III) oxide reacting with hydrogen sulfide to form arsenic sulfide (\( As_2S_3 \)). 
Step 2: Balancing the Reaction 
\[ As_2O_3 + 3H_2S \rightarrow As_2S_3 + 3H_2O \] Here, arsenic oxide is reduced to arsenic sulfide while hydrogen sulfide is oxidized. 
Final Answer: The sol formed in this reaction is arsenic sulfide (\( As_2S_3 \)).

Answer 2

The sol formed in the reaction between arsenic(III) oxide and hydrogen sulfide is arsenic trisulfide (As₂S₃):

When arsenic(III) oxide (As₂O₃) reacts with hydrogen sulfide (H₂S), a double displacement reaction occurs, leading to the formation of arsenic trisulfide (As₂S₃), which is an insoluble colloidal substance known as a sol.

This sol is a typical example of a sulfur compound precipitate that forms as a colloidal dispersion in water.

The unbalanced reaction is:
As₂O₃ + H₂S → As₂S₃ + H₂O

Here, As₂S₃ is the characteristic yellow-orange sol formed.

Such reactions are important in qualitative inorganic analysis to identify arsenic compounds through their sulfide precipitates.