[Chemistry Class Notes] on Carbon Dioxide Pdf for Exam

Carbon dioxide is a naturally occurring chemical compound that plays an integral role in the Earth’s ecosystem. It is essential for photosynthesis, which all plants need to survive. Carbon dioxide also helps regulate the temperature of the atmosphere and the planet as well. They are often referred to as greenhouse gases because they allow sunlight to enter but do not allow it to leave, thus heating the lower atmosphere. Carbon dioxide is abundant in the Earth’s atmosphere (amounting to about 393 ppm, or parts per million) and plays a vital role in regulating global climate. It helps trap heat near the Earth’s surface, meaning that less of it escapes into space. This makes it easier for life on Earth to thrive. It also helps drive the carbon cycle, which is essential for life on Earth to exist.

Increased Concentration of Carbon Dioxide

Humans have played a significant role in increasing the concentration of this gas by burning fossil fuels and clearing forests, among other activities. Burning fossil fuels returns carbon dioxide to Earth’s atmosphere after it was stored deep underground over millions of years, while deforestation reduces the number of plants that absorb it. Despite this, natural sources of carbon dioxide are much larger than artificial ones.

Carbon dioxide is believed to cause negative health effects in large concentrations, but the possible consequences of living with lower levels have not yet been studied extensively. However, most scientists agree that it would be dangerous for humans to breathe air containing higher concentrations of carbon dioxide than they have in the past.

Carbon Dioxide Definition

Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms bonded together. It is one of the important ingredients in photosynthesis, the process by which green plants prepare food and energy. It is a colourless, odourless gas and is soluble in water, ethanol, and acetone. It has a melting point of -55.6°C and has a boiling point of -78.5°C. It has a density of 1.977g/ml.

Carbon Dioxide as a Greenhouse Gas

Carbon dioxide is an important greenhouse gas that helps to trap heat in our atmosphere, but it is a minor component of Earth’s atmosphere. Atmospheric CO₂ can be extracted from natural sources like volcanic outgassing, combustion of organic matter, and the respiration processes of living aerobic organisms, and man-made sources of carbon dioxide can be obtained from the burning of fossil fuels for power generation and transport use. It reacts with water to produce carbonic acid. It reacts with alkalis to give carbonates and bicarbonates as a product. It is also produced by fermentation and cellular respiration. In this topic, we have discussed the CO₂ definition. Now we will study about properties and uses of carbon dioxide.

Properties of Carbon Dioxide

• It is a colourless and odourless gas.

• It is a non-flammable gas.

• It is slightly toxic.

• It is denser than air.

•  It has a melting point of -55.6°C and has a boiling point of -78.5°C.

•  It has a density of 1.977g/ml.

• It is soluble in water, solubility decreases as temperature increases.

• It forms a weak carbonic acid when dissolved in water. It turns lime water milky.

• Equation which shows CO₂ behaves as an acid:

CO₂ + H₂O → H₂CO₃ → H+(aq) + HCO₃^–(aq)

             (The reaction is reversible in nature).

CO₂ + NaOH → NaHCO₃

NaHCO₃​ +NaOH ⇒ Na₂CO₃ +H₂O

Now, let us know about some uses of CO₂ gas.

Carbon Dioxide Uses

• Plants convert carbon dioxide to oxygen during a process called photosynthesis, using both carbon and oxygen to make carbohydrates.

• Carbon dioxide is also used as a refrigerant.

• It is used as a fire extinguisher.

• It is used in promoting the growth of plants in greenhouses.

• It is used in carbonated beverages, soft drinks, and beers to make them fizzy.

• Large quantities of solid carbon dioxide ( in the form of dry ice) are used in large-scale refrigeration.

• It is one of the parts of medical gases because it promotes exhalation.

• The Carbon dioxide released by baking powder or yeast that makes cake batter rise is the best example of the use of carbon dioxide in everyday life.

Harmful Effects of Carbon Dioxide

Due to several human activities, the amount of CO₂ released into the atmosphere has been rising extensively during the past few years. There has been an increase in carbon dioxide concentrations in the atmosphere from about 280 ppm in 1850 to 364 ppm in 1998. The main reason is due to human activities during and after the industrial revolution. Humans have been increasing the amount of carbon dioxide in the air by burning fossil fuels, producing cement, deforestation, and by carrying out land clearing and forest combustion. About 24% of the current atmospheric CO₂ concentrations exist due to these human activities, considering that there is no change in natural amounts of carbon dioxide. 

Emissions released from the burning of fossil fuels combine with moisture in the air. The result is precipitation with high acid content. This increase in CO₂ is harmful to humans, aquatic animals, and plants. Incomplete combustion or burning of carbon-containing fuels, such as coal, oil, charcoal, wood, kerosene, leads to the formation of Carbon Monoxide.

Carbon Monoxide

Carbon monoxide is a highly poisonous gas. It is a colourless and odourless gas, and its presence is detected immediately. If inhaled, carbon monoxide readily combines with the haemoglobin of our blood. Haemoglobin helps in carrying oxygen from the lungs to the tissues. Oxygen combines with haemoglobin to form o
xy-haemoglobin. Similarly, CO combines with haemoglobin to form carboxyhemoglobin.

The affinity of CO for haemoglobin is much more (about 200 times) than that of oxygen. In the presence of carbon monoxide, the oxygen-carrying capacity of the haemoglobin is decreased. The deficiency of oxygen in the blood can cause headaches, dizziness, cardiac and respiratory problems, and even death. Because of this reason, it is dangerous to sleep in a closed room with a coke fire burning inside because the burning coke in an insufficient supply of oxygen produces a lot of carbon monoxide that can cause death.

Preventive Measures

• Moving to renewable sources of energy like solar energy, wind energy, etc., will reduce the use of fossil fuels. This will reduce the release of carbon dioxide into the atmosphere.

• Planting more trees on a large scale can help in decreasing the release of carbon dioxide into the atmosphere.

• The government should come up with strict policies to maintain the overall air quality of the city.

Conclusion

Carbon dioxide is one of the major causes of climate change. There are several harmful effects of carbon dioxide on humans, animals, and plants. Reducing human activities that release carbon dioxide into the atmosphere will reduce the effects of global warming. Global warming is a major concern for the coming years. The release of carbon dioxide from human activities, deforestation, land-use changes and from use of fossil fuels is changing the face of our planet. Carbon dioxide is one of the greenhouse gases that contribute to global warming. It accounts for about 80% of total U.S. greenhouse gas (GHG) emissions, which makes it a very important target when considering potential GHG mitigation strategies. Carbon dioxide has been increasing in the Earth’s atmosphere since the Industrial Revolution and is now at its highest level in at least 800,000 years.