Question

Crude gunpowders often contain a mixture of potassium nitrate and charcoal (carbon). When such a mixture is heated until reaction occurs, a solid residue of potassium carbonate is produced. The explosive force of the gunpowder comes from the fact that two gases are also produced (carbon monoxide and nitrogen), which increase in volume with great force and speed. Write the unbalanced chemical equation for the process.

Short answer

The unbalanced chemical equation for the reaction between potassium nitrate (KNO₃) and charcoal (carbon, C) upon heating, producing potassium carbonate (K₂CO₃), carbon monoxide (CO), and nitrogen (N₂) is: KNO₃ (s) + C (s) → K₂CO₃ (s) + CO (g) + N₂ (g)

Step-by-step solution

Identify Chemical Formulas

First, we need to identify the chemical formulas of the reactants and products as given: 1. Potassium nitrate: KNO₃ 2. Charcoal (carbon): C 3. Potassium carbonate: K₂CO₃ 4. Carbon monoxide: CO 5. Nitrogen: N₂

Write the Unbalanced Chemical Equation

Now we can write the unbalanced chemical equation using these formulas: KNO₃ (s) + C (s) → K₂CO₃ (s) + CO (g) + N₂ (g) Here, (s) denotes a solid substance and (g) denotes a gaseous substance. This is the unbalanced chemical equation for the reaction between potassium nitrate and charcoal described in the exercise.

Key concepts

Potassium Nitrate

Potassium nitrate, often referred to as saltpeter, is an important compound in chemistry. Primarily known for its role in gunpowder production, it is composed of potassium, nitrogen, and oxygen with the chemical formula \(KNO_3\). Potassium nitrate is a white crystalline substance. It's a strong oxidizer, meaning it can donate oxygen in chemical reactions.
This characteristic makes it very useful in processes where rapid oxidation, such as combustion, is needed.

• Used in fertilizers
• Helps preserve food
• Essential for certain fireworks and pyrotechnics

Its ability to release oxygen helps fuel other substances, such as charcoal, allowing explosive reactions to occur.

Charcoal

Charcoal, a form of carbon, plays a crucial role in reactions where it acts as a reducing agent. In chemistry, a reducing agent donates electrons to another substance. Charcoal is composed almost entirely of carbon atoms, but its structure is porous and impure due to the way it's produced.
In the reaction with potassium nitrate, charcoal provides the fuel needed for the combustion process.

• Charcoal is produced by heating wood or other organic materials in the absence of oxygen
• It's widely used for grilling and barbecuing because of its high heat output and low cost
• It serves as a source of carbon in chemical reactions

With potassium nitrate, the oxidation of charcoal leads to the formation of various products including potassium carbonate.

Potassium Carbonate

Potassium carbonate is a compound formed as a solid residue when potassium nitrate reacts with charcoal. It appears as a white salt and is essential in various industrial applications. Represented by the formula \(K_2CO_3\), it's also known as "potash."
During gunpowder reactions, potassium carbonate forms alongside gaseous products, playing a critical role in the chemical transformation.

• Used in glass production
• Acts as a mild drying agent
• Serves in the production of soft soaps

It's one of the reaction's main solid residues, highlighting the role of chemical balance in gunpowder compositions.

Gas Production

Gas production in the reaction between potassium nitrate and charcoal is central to understanding why gunpowder has explosive properties. During this chemical reaction, two primary gases are released: carbon monoxide \(CO\) and nitrogen \(N_2\).
These gases rapidly expand in volume, which contributes to the explosive power of gunpowder.

• Carbon monoxide is a toxic gas, but in this context, it's part of the explosive mixture
• Nitrogen is an inert gas that supports the rapid expansion

When the solid reactants turn into gaseous products, the significant increase in volume causes pressure build-up, leading to an explosion. This transformation is an example of a rapid exothermic reaction, releasing energy quickly.