Question

A person was found dead of carbon monoxide poisoning in a well-insulated cabin. Investigation showed that he had used a blackened bucket to heat water on a butane burner. The burner was found to function properly with no leakage. Explain, with an appropriate equation, the cause of his death.

Short answer

Incomplete combustion of butane led to carbon monoxide accumulation, causing death.

Step-by-step solution

Identify Fuel Combustion Reaction

Butane, which is \\( C_4H_{10} \), burns in the presence of oxygen to produce carbon dioxide and water in a complete combustion. The chemical equation for complete combustion of butane is: \[ 2C_4H_{10} + 13O_2 \rightarrow 8CO_2 + 10H_2O \] However, in inadequate oxygen supply, incomplete combustion occurs resulting in carbon monoxide (\( CO \)) as one of the products.

Examine Incomplete Combustion

In a limited oxygen environment, such as a well-insulated cabin with poor ventilation, butane combustion can be incomplete. This results in the production of carbon monoxide (CO). The reaction for incomplete combustion of butane can be represented as:\[ 4C_4H_{10} + 13O_2 \rightarrow 8CO + 2CO_2 + 10H_2O \]

Understand Carbon Monoxide Poisoning

Carbon monoxide is a colorless, odorless gas that binds with the hemoglobin in the blood more effectively than oxygen. This forms carboxyhemoglobin, which reduces blood's capacity to carry oxygen, leading to symptoms of poisoning or death.

Conclude the Cause of Death

The lack of adequate ventilation in the cabin likely allowed carbon monoxide to accumulate. Given its reduced oxygen carrying capacity when carboxyhemoglobin forms, the victim succumbed to carbon monoxide poisoning due to inhalation of the gas.

Key concepts

Incomplete Combustion

Incomplete combustion occurs when there is not enough oxygen present for a fuel to react completely with oxygen to form carbon dioxide and water. When there's insufficient oxygen, carbon-based fuels like butane may produce carbon monoxide instead. This process results in a less efficient reaction, often releasing carbon particles seen as soot or smoke.

Some common signs of incomplete combustion include:

• Blackened appliances, as seen in this case with the bucket.
• An increase in dangerous pollutants such as carbon monoxide.

Understanding how incomplete combustion occurs is important in preventing related dangers, like carbon monoxide poisoning.

Butane Combustion

Butane is a type of hydrocarbon with the chemical formula \( C_4H_{10} \). When it combusts in the presence of sufficient oxygen, it produces carbon dioxide and water. However, in a confined space with limited air supply, butane undergoes incomplete combustion.

The complete combustion of butane can be represented by the equation:\[2C_4H_{10} + 13O_2 \rightarrow 8CO_2 + 10H_2O\]Conversely, the incomplete combustion equation would be:\[4C_4H_{10} + 13O_2 \rightarrow 8CO + 2CO_2 + 10H_2O\]
Understanding these reactions helps in recognizing why CO is produced when there is insufficient oxygen.

Carboxyhemoglobin

Carboxyhemoglobin is formed when carbon monoxide binds to hemoglobin in red blood cells. This bond is over 200 times stronger than the bond formed with oxygen. As a result, when carboxyhemoglobin forms, oxygen transport in the body is severely restricted, leading to potential poisoning.

Symptoms of carbon monoxide poisoning can vary:

• Headache or dizziness.
• Nausea and confusion.
• In serious cases, unconsciousness or death.

Being aware of these effects is crucial for identifying and preventing CO poisoning incidents.

Oxygen Supply

For combustion reactions, a steady supply of oxygen is crucial. In scenarios like the cabin incident, the limited supply of oxygen results in the incomplete combustion of fuels like butane. Without adequate oxygen, burning efficiency is reduced, causing an increased risk of carbon monoxide production.

Ways to ensure proper oxygen supply:

• Use in open or well-ventilated spaces.
• Avoid using burners or heaters in confined areas.

Ensuring there's enough oxygen present can significantly lower the risk of dangerous emissions.

Ventilation

Ventilation is the process of supplying fresh air to a space while removing stale air. In the context of combustion, it's crucial to provide a constant oxygen supply to prevent incomplete combustion. Poor ventilation, such as in a well-insulated cabin, can lead to an accumulation of carbon monoxide. Effective ventilation strategies include:

• Opening windows and doors when using appliances that burn fuel.
• Installing ventilation systems or fans to promote air circulation.

Good ventilation practices can mitigate the risks associated with the use of gas-powered heaters and stoves.