Problem 5 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is formed when sodium sulphate is boiled with powered sulphur? (a) \(\mathrm{NaHSO}_{4}\) (b) \(\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}\) (c) \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) (d) \(\mathrm{Na}_{2} \mathrm{~S}_{4} \mathrm{O}_{6}\)

Step-by-Step Solution

Answer

The product formed is \( \mathrm{Na}_2\mathrm{S}_2\mathrm{O}_3 \) (sodium thiosulphate).

Step 1: Identify Reactants

The reactants in this chemical reaction are sodium sulphate (\( \mathrm{Na}_2\mathrm{SO}_4 \)) and powdered sulphur (\( \mathrm{S} \)). We are tasked with identifying the product of this chemical reaction when boiled together.

Step 2: Analyze Potential Reactions

When sodium sulphate is heated with powdered sulphur, it's possible for sulphur to react with the sulfate ion to form a compound that may include polyatomic ions such as thiosulphate or dithionate, given the options provided.

Step 3: Consider Reactants' Interactions

When sulphate \((\mathrm{SO}_4^{2-})\) and sulphur \( (\mathrm{S}) \) are heated, one likely reaction involves the conversion of some sulfate to thiosulfate (\(\mathrm{S}_2\mathrm{O}_3^{2-}\)) due to the incorporation of sulphur atoms.

Step 4: Identify the Product

Given the choices, heating sodium sulphate with sulphur is most likely to produce sodium thiosulphate \((\mathrm{Na}_2\mathrm{S}_2\mathrm{O}_3)\). This compound is formed in reactions involving addition of sulphur to the sulfate group.

Key Concepts

Thiosulphate Formation

Thiosulphate formation is an intriguing chemical process that occurs when sodium sulphate is heated with powdered sulphur. In simpler terms, this reaction involves the interaction between sulphur and the sulphate ion, creating a change in the chemical makeup of the original compound. When we heat sodium sulphate (\(\mathrm{Na}_2\mathrm{SO}_4\)) and introduce powdered sulphur (\(\mathrm{S}\)), an important transformation happens. Some of the sulphate ions combine with sulphur to form thiosulphate ions (\(\mathrm{S}_2\mathrm{O}_3^{2-}\)). This is due to the addition of sulphur atoms into the sulphate structure. The new compound formed, sodium thiosulphate (\(\mathrm{Na}_2\mathrm{S}_2\mathrm{O}_3\)), is the result of this specific chemical interaction.

Understanding this process provides insight into how adding elements to a compound can significantly alter its chemical structure and properties. This transformation of compounds is a staple in chemical reactions, offering a vivid example of composition change resulting from a reaction.

Chemical Reaction Analysis

Chemical reaction analysis involves breaking down complex reactions to understand the interactions between different elements and compounds. When asked to predict the product of a chemical reaction, like sodium sulphate boiled with powdered sulphur, we follow a systematic approach.

• Identify the reactants: Sodium sulphate (\(\mathrm{Na}_2\mathrm{SO}_4\)) and sulphur (\(\mathrm{S}\)).
• Analyze the possible interactions: Here, the potential for sulphur to convert sulphate into new products such as thiosulphate is explored.
• Determine probable outcomes: Sodium thiosulphate is identified as a likely product due to its formation through sulphur's integration into the sulphate ion.

Each step in this process involves leveraging known chemical principles to anticipate how different substances will react. By analyzing these reactions, we can not only predict outcomes but also understand the mechanisms driving these chemical changes. This process helps students and chemists alike develop a deeper understanding of chemical behavior and reactivity.

Polyatomic Ions

Polyatomic ions are charged entities composed of two or more atoms covalently bonded, and they act as a single ion. In the context of our exercise, understanding polyatomic ions like the sulphate (\(\mathrm{SO}_4^{2-}\)) and thiosulphate (\(\mathrm{S}_2\mathrm{O}_3^{2-}\)) ions is crucial.

Sulphate is a common polyatomic ion often involved in various chemical reactions. When subjected to heat alongside powdered sulphur, sulphate can transform into other polyatomic ions like thiosulphate. The addition of extra sulphur atoms alters the chemical formula and properties of the ion.

• Thiosulphate is an example of how adding atoms to a base polyatomic ion introduces new chemical characteristics.
• These ions contribute significantly to the reactivity and the nature of the resulting compound.

Polyatomic ions play diverse roles in chemistry, serving as key components in reactions and playing influential roles in determining the properties and behavior of compounds. Mastering the concept of polyatomic ions enables learners to predict and comprehend the outcomes of various chemical reactions accurately.