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Difficulty: EasySulfur Allotropes, Hydrogen Sulfide, and Sulfur(IV) Oxide

Complete the following statement regarding the qualitative test for hydrogen sulfide gas by filling in the missing physical characteristic of the precipitate formed.

Answer:When hydrogen sulfide gas (H2SH_2S) is bubbled into an aqueous solution of lead(II) ethanoate, a insoluble 【black】 precipitate of lead(II) sulfide (PbSPbS) is observed.

Answer

black
When hydrogen sulfide gas comes into contact with lead(II) ethanoate, lead(II) sulfide (PbSPbS) is formed. Lead(II) sulfide is insoluble in water and has a characteristic black color, making 'black' the correct term to complete the sentence.

Step-by-Step Solution

1
Identify the chemical reaction between hydrogen sulfide gas (H2SH_2S) and aqueous lead(II) ethanoate solution ((CH3COO)2Pb(CH_3COO)_2Pb).
The double displacement reaction produces lead(II) sulfide precipitate (PbSPbS) and ethanoic acid (CH3COOHCH_3COOH).
The equation is: (CH3COO)2Pb(aq)+H2S(g)→PbS(s)+2CH3COOH(aq)(CH_3COO)_2Pb_{(aq)} + H_2S_{(g)} \rightarrow PbS_{(s)} + 2CH_3COOH_{(aq)}.
2
Determine the physical property (color) of the resulting lead(II) sulfide precipitate.
Lead(II) sulfide (PbSPbS) is a distinct black solid.
This specific color change is the standard laboratory confirmatory test for identifying H2SH_2S gas.

Key Concept

Qualitative test for hydrogen sulfide gas using lead(II) ethanoate paper or solution
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Topics

Sulfur Allotropes, Hydrogen Sulfide, and Sulfur(IV) Oxide

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