Question

Carbon decomposes potassium carbonate into (a) \(\mathrm{C}\) (b) \(\mathrm{O}\) (c) \(\mathrm{KCN}\) (d) \(\mathrm{K}\)

Short answer

(c) \(\mathrm{KCN}\)

Step-by-step solution

Understand the problem

We need to determine the product that forms when carbon ( ext{C}) decomposes potassium carbonate ( ext{K}_2 ext{CO}_3).

Recall the decomposition reaction

Potassium carbonate typically decomposes into potassium oxide ( ext{K}_2 ext{O}) and carbon dioxide ( ext{CO}_2) when heated. Thus, the reaction is: \( ext{K}_2 ext{CO}_3 ightarrow ext{K}_2 ext{O} + ext{CO}_2\)

Consider the effect of carbon

When carbon is introduced, it can further react with the carbon dioxide product to form potassium cyanide ( ext{KCN}). The reaction is: \( ext{C} + ext{CO}_2 + ext{K}_2 ext{O} ightarrow 2 ext{KCN}\)

Identify the final product

Since carbon and carbon dioxide react together with potassium oxide, the final product of the decomposition of potassium carbonate in the presence of carbon is potassium cyanide ( ext{KCN}).

Key concepts

Potassium Carbonate

Potassium carbonate is an important chemical compound with the formula \(\mathrm{K}_2\mathrm{CO}_3\). It is commonly known as potash. Potassium carbonate is a white salt, soluble in water, which forms a strongly alkaline solution. It is deliquescent, meaning it can absorb water from the environment, often forming a liquid solution.This compound is used extensively in various industrial processes. Some common applications include:

• Glass Manufacturing: It helps to lower the melting point of silica in glass production.
• Soap and Detergents: It is used in the production of soaps to make them softer and more soluble.
• Food Industry: Utilized as a drying agent and to adjust pH levels.
• Chemical Reactions: Acts as a reagent in laboratories and for various applications.

When heated, potassium carbonate undergoes a decomposition reaction, breaking down into potassium oxide \(\mathrm{K}_2\mathrm{O}\) and carbon dioxide \(\mathrm{CO}_2\). This is the first step in understanding its reaction mechanism, especially when carbon is involved.

Potassium Cyanide

Potassium cyanide, represented by the formula \(\mathrm{KCN}\), is an extremely potent chemical known for its applications in gold mining, organic synthesis, and electroplating.It appears as a white crystalline compound and is highly soluble in water. Caution: It is highly toxic, and extreme care should be taken when handling it.The role of potassium cyanide in reactions is quite fascinating. During the decomposition of potassium carbonate in the presence of carbon, something interesting happens. The carbon interacts with carbon dioxide (itself a product of the decomposition) in the presence of potassium oxide. This combination unexpectedly results in the formation of potassium cyanide \(\mathrm{KCN}\).This reaction outlines the importance of considering all possible interactions in a chemical process, particularly those involving carbon, due to its variety of oxidation states and versatile bonding properties.

Reaction Mechanism

Understanding reaction mechanisms is fundamental in chemistry as they provide insight into how compounds interact and transform. In the case of potassium carbonate decomposition, we observe a sequence of transformations that lead to unexpected products when additional elements or compounds are introduced.
The decomposition of potassium carbonate \(\mathrm{K}_2\mathrm{CO}_3\) begins when it breaks down into potassium oxide \(\mathrm{K}_2\mathrm{O}\) and carbon dioxide \(\mathrm{CO}_2\). This is a classic decomposition reaction where a single compound dissociates into simpler substances.However, when carbon \(\mathrm{C}\) is added to the mix, it reacts with the evolved carbon dioxide to form carbon monoxide \(\mathrm{CO}\), which then interacts with the potassium oxide. This extra step forms potassium cyanide \(\mathrm{KCN}\), showcasing the complexity and dynamic nature of chemical reactions. Reaction mechanisms help chemists predict and explain the products of a reaction under different conditions by outlining each step of the process. In the presence of carbon, the mechanism not only alters the expected course of decomposition but also creatively utilizes the by-products to synthesize a useful compound.