Problem 46 - General Chemistry: Principles and Modern Applications

Question

Show how you would use elemental sulfur, chlorine gas, metallic sodium, water, and air to produce aqueous solutions containing (a) \(\mathrm{Na}_{2} \mathrm{SO}_{3} ;\) (b) \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) (c) \(\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3} .\) [Hint: You will have to use information from other chapters as well as this one.].

Step-by-Step Solution

Answer

The solution to the given problem is the three reactions: (a) \(S + O_2 + 2Na \rightarrow Na_2SO_3\), (b) \(2Na_2SO_3 + O_2 \rightarrow 2Na_2SO_4\), and for (c) first \(S + O_2 \rightarrow SO_2,\) and \(S + Cl_2 \rightarrow SCl_2\), then \(SO_2 + SCl_2 + 2Na + H_2O \rightarrow Na_2S_2O_3 + 2HCl\).

Step 1: Solving for \(Na_2SO_3\)

The first compound to produce is \(Na_2SO_3\). The starting reactant is sulfur. Upon reacting with oxygen in the air and sodium, sulfur forms sodium sulfite. The reaction is as follows: \[S + O_2 + 2Na \rightarrow Na_2SO_3\]

Step 2: Solving for \(Na_2SO_4\)

To produce \(Na_2SO_4\), we start with \(Na_2SO_3\), the product from the previous step, and react it with oxygen. This forms the required product, sodium sulfate. The reaction can be written as: \[2Na_2SO_3 + O_2 \rightarrow 2Na_2SO_4\]

Step 3: Solving for \(Na_2S_2O_3\)

The third compound \(Na_2S_2O_3\) requires a two-step process starting from sulfur. Firstly, sulfur reacts with oxygen in the air and chlorine to form sulfur dioxide and sulfur monochloride: \[S + O_2 \rightarrow SO_2,\] \[S + Cl_2 \rightarrow SCl_2\]. In the next step, these products react with water and sodium to form sodium thiosulfate and other by-products. The reactions are as follows: \[SO_2 + SCl_2 + 2Na + H_2O \rightarrow Na_2S_2O_3 + 2HCl\]

Key Concepts

Sodium Compounds

Sodium compounds are a group of chemical compounds that contain the element sodium, denoted by the symbol "Na". These compounds are prevalent in the chemical industry, with each having unique properties and applications.
For example, sodium sulfite (\( Na_2SO_3 \)) is a compound used in the paper and pulp industry as a preservative and bleaching agent. Its production involves reacting sodium metal with sulfur and oxygen. On the other hand, sodium sulfate (\( Na_2SO_4 \)) is commonly used in detergents and has an important role as a drying agent. It is created by oxidizing sodium sulfite with additional oxygen. Lastly, sodium thiosulfate (\( Na_2S_2O_3 \)) is notable for its use in photography and as a treatment to eliminate chlorine in swimming pools. It is synthesized through a more complex reaction involving sulfur dioxide, sulfur monochloride, and sodium.

• Sodium sulfite: \( Na_2SO_3 \)
• Sodium sulfate: \( Na_2SO_4 \)
• Sodium thiosulfate: \( Na_2S_2O_3 \)

Each of these sodium compounds incorporates sodium in a way that influences the compound's characteristics and uses.

Sulfur Reactions

Sulfur, a non-metal element, often reacts with other elements to form sulfides, sulfites, and sulfates. These reactions are significant in producing various sodium compounds.
One primary reaction involving sulfur is its combination with oxygen, forming sulfur dioxide (\( SO_2 \)), which is a precursor for many industrial processes. In addition, when sulfur reacts with chlorine, it forms sulfur monochloride (\( SCl_2 \)), a versatile reagent in chemical synthesis.
These reactions involving sulfur are integral to creating different sodium compounds. Sulfur's ability to form multiple oxidation products allows for a diverse range of chemical transformations.

• Reaction with oxygen forms sulfur dioxide: \( S + O_2 \rightarrow SO_2 \)
• Reaction with chlorine forms sulfur monochloride: \( S + Cl_2 \rightarrow SCl_2 \)

Understanding these fundamental sulfur reactions is crucial for grasping the production of sodium-based compounds through advanced chemical synthesis.

Aqueous Solutions

Aqueous solutions play a vital role in chemistry, referring to substances dissolved in water. Water, as a solvent, facilitates numerous chemical reactions and processes.
When sodium compounds, such as sodium sulfite (\( Na_2SO_3 \)), sodium sulfate (\( Na_2SO_4 \)), and sodium thiosulfate (\( Na_2S_2O_3 \)), are dissolved in water, they form aqueous solutions. These solutions are characterized by the ability of these compounds to dissociate into ions. For instance, (\( Na_2SO_3 \)) in an aqueous solution dissociates into sodium (\( Na^+ \)) and sulfite ions (\( SO_3^{2-} \)).

• Sodium ions: \( 2Na^+ \)
• Sulfite ions: \( SO_3^{2-} \)

Aqueous solutions of sodium compounds are practical in applications like chemical reactions, industrial processes, and lab experiments because they offer a convenient medium for substances to interact and react while being evenly distributed in water.