Question

The poisonous gas present in the exhaust fumes of car is (a) \(\mathrm{CO}_{2}\) (b) \(\mathrm{CO}\) (c) \(\mathrm{CH}_{4}\) (d) \(\mathrm{C}_{2} \mathrm{H}_{2}\)

Short answer

The poisonous gas in car exhaust fumes is carbon monoxide ( \mathrm{CO} ).

Step-by-step solution

Understanding the Problem

We need to determine which of the given gases is poisonous and commonly found in car exhaust fumes. The options are (a) Carbon dioxide (b) Carbon monoxide (c) Methane (d) Acetylene. We will analyze each to see which is likely to be the poisonous gas.

Analyzing Each Option

(a) \(\mathrm{CO}_{2}\) - Carbon dioxide is a non-toxic gas produced during combustion but is not considered poisonous at typical concentrations. (b) \(\mathrm{CO}\) - Carbon monoxide is a colorless, odorless, and highly toxic gas produced by incomplete combustion. It binds with hemoglobin in blood, reducing oxygen supply to the body.(c) \(\mathrm{CH}_{4}\) - Methane is a non-toxic gas and is not typically a major component of exhaust fumes.(d) \(\mathrm{C}_{2}\mathrm{H}_{2}\) - Acetylene is used as a fuel and is not typically found in car exhaust.

Conclusion

Based on the analysis, carbon monoxide (b) \(\mathrm{CO}\) is the poisonous gas found in car exhaust fumes due to incomplete combustion.

Key concepts

Incomplete Combustion

Cars run on engines that burn fuel to produce energy. Ideally, this process should result in the complete burning of fuel, primarily producing carbon dioxide (\(\mathrm{CO}_2\)) and water (\(\mathrm{H}_2\mathrm{O}\)). However, due to various conditions within the engine, the combustion process often remains incomplete. This incomplete combustion results when there is not enough oxygen to react with the fuel fully.
During incomplete combustion, instead of all carbon atoms in the fuel forming \(\mathrm{CO}_2\), some of them form carbon monoxide (\(\mathrm{CO}\)). This happens because the lack of oxygen prevents the fuel from breaking down completely. Sometimes, small amounts of other hydrocarbons can also be present. The inability to achieve full combustion is a key reason for the presence of carbon monoxide in vehicle emissions.
In addition to the engineering challenges, other factors such as poor engine maintenance, suboptimal fuel-air mixtures, and cold starts where the engine is working hard to warm up can exacerbate incomplete combustion. By ensuring that engines are well-tuned and regularly maintained, drivers can help reduce the occurrence of incomplete combustion, thus minimizing carbon monoxide emissions.

Toxic Gases

Some gases pose significant health risks, especially when inhaled. Carbon monoxide (\(\mathrm{CO}\)), found in car exhaust, is a toxic gas. Unlike oxygen, which is essential for life, carbon monoxide can be extremely harmful. It is colorless and odorless, making it particularly dangerous as it can go undetected until it's too late.
When inhaled, carbon monoxide binds with hemoglobin in the blood to form carboxyhemoglobin. This compound prevents hemoglobin from carrying oxygen efficiently. As a result, the body's cells and tissues receive less oxygen, leading to symptoms like dizziness, headaches, fatigue, and in extreme cases, can cause death.
The toxicity level depends on the concentration of carbon monoxide and the duration of exposure. Even low levels can be harmful over prolonged periods. Other gases like methane (\(\mathrm{CH}_4\)) and acetylene (\(\mathrm{C}_2\mathrm{H}_2\)) also exist but are much less toxic compared to carbon monoxide. That's why efforts to reduce \(\mathrm{CO}\) emissions are crucial for public health and environmental sustainability.

Car Exhaust Pollutants

The exhaust emitted by car engines contains several pollutants, substances that contribute to air quality degradation and pose health risks. The principal pollutant of concern arising from incomplete combustion is carbon monoxide (\(\mathrm{CO}\)). In addition to \(\mathrm{CO}\), car exhaust can also release nitrogen oxides (\(\mathrm{NO}_x\)), volatile organic compounds (VOCs), particulate matter, and hydrocarbons.
Each of these pollutants has different origins and impacts. For example:

• Nitrogen oxides (\(\mathrm{NO}_x\)) form when fuel is burned at high temperatures, and they can lead to respiratory issues and contribute to smog formation.
• Volatile Organic Compounds (VOCs) are precursors to ozone and are produced through fuel evaporation or as a by-product of fuel combustion.
• Particulate matter can arise from unburned fuel particles and contributes to respiratory ailments.

Fortunately, car manufacturers are developing technologies like catalytic converters and improved fuel injection systems that help minimize these emissions. Regular vehicle inspections and maintenance are also essential to ensure that cars operate efficiently and release fewer pollutants.