Question

Which of the following do not undergo disproportionation on hcating with caustic soda? (1) Chlorine (2) Silicon (3) Phosphorous (4) Sulphur

Short answer

Silicon does not undergo disproportionation with caustic soda.

Step-by-step solution

- Define Disproportionation

Disproportionation is a type of redox reaction in which a single substance is simultaneously oxidized and reduced, forming two different products.

- List Possible Disproportionation Reactions

Analyze the reactions of chlorine, silicon, phosphorous, and sulfur with caustic soda (NaOH) to see which undergo disproportionation.

- Examine Chlorine Reaction

When chlorine reacts with caustic soda, it forms sodium chloride (NaCl) and sodium hypochlorite (NaOCl) through disproportionation: Therefore, chlorine undergoes disproportionation.

- Examine Silicon Reaction

Silicon does not react with caustic soda under standard conditions to undergo disproportionation. It primarily forms silicates in high pH environments.

- Examine Phosphorous Reaction

Phosphorous (especially white phosphorous) can undergo disproportionation when reacting with caustic soda to form phosphine ( phosphoric acid and phosphine ( formation of phosphoric acid and phosphine ( ( H3PO4 and phosphine ( PH3.

- Examine Sulphur Reaction

Sulphur undergoes disproportionation with caustic soda to form sodium sulfide ( ( and sodium sulfite (So2S). Therefore, sulfur also undergoes disproportionation.

- Identify the Non-Disproportionating Element

From the analysis, silicon is the element that does not undergo disproportionation when heated with caustic soda.

Key concepts

disproportionation

Disproportionation is an important concept in chemistry, particularly in redox reactions. In a disproportionation reaction, a single element in a reactant is simultaneously oxidized and reduced. This means the element increases and decreases its oxidation state in one process, creating two different products. For instance, when chlorine reacts with caustic soda, it forms both sodium chloride and sodium hypochlorite. This simultaneous oxidation and reduction within a single reactant is what characterizes disproportionation. It is crucial to distinguish disproportionation from other redox processes where oxidation and reduction occur between different substances.

redox reactions

Redox reactions (oxidation-reduction reactions) are processes where electrons are transferred between chemical species. In oxidation, a substance loses electrons, while in reduction, a substance gains electrons. Redox reactions are essential for understanding disproportionation. For example, in the reaction of chlorine with caustic soda, chlorine is both oxidized and reduced. Redox reactions are fundamental in many chemical processes, from energy production in batteries to metabolic pathways in biology. Understanding redox processes helps in identifying and predicting chemical behavior and reaction outcomes.

caustic soda reactions

Caustic soda, also known as sodium hydroxide (NaOH), is a strong base used in various reactions. It plays a significant role in disproportionation reactions due to its ability to provide a high pH environment. For example, when chlorine reacts with caustic soda, it disproportionates to form sodium chloride and sodium hypochlorite. Similarly, when sulfur interacts with caustic soda, it forms sodium sulfide and sodium sulfite. Understanding the reactivity of caustic soda is crucial for predicting how different elements will behave in its presence.

chlorine reactions

Chlorine is a halogen that readily participates in disproportionation reactions. When chlorine reacts with caustic soda, it disproportionates to form two products: sodium chloride (NaCl) and sodium hypochlorite (NaOCl). This reaction is typically represented as: