Question

Carbon dioxide is a gas found in our atmosphere. a. What is the approximate concentration? b. Why is its concentration in the atmosphere increasing? c. Draw the Lewis structure for the \(\mathrm{CO}_{2}\) molecule. d. Would you expect carbon dioxide to be highly soluble in seawater? Explain.

Short answer

a. About 415 ppm. b. Due to fossil fuel combustion and deforestation. c. O=C=O. d. Somewhat soluble, forming carbonic acid.

Step-by-step solution

Understanding Carbon Dioxide Concentration

The concentration of carbon dioxide in the atmosphere is typically measured in parts per million (ppm). As of recent measurements, it is approximately 415 ppm. This value can vary slightly based on the location and time of year due to natural sources and sinks, such as plant photosynthesis and seasonal emissions.

Reasons for Increasing Concentration

The concentration of carbon dioxide in the atmosphere is rising, mainly due to human activities. Combustion of fossil fuels (such as coal, oil, and natural gas) for energy and transportation is the primary contributor. Additionally, deforestation leads to higher levels of CO2 because fewer trees are available to absorb carbon dioxide.

Drawing the Lewis Structure of CO extsubscript{2}

To draw the Lewis structure of CO extsubscript{2}, start by determining the total number of valence electrons. Carbon (C) has 4 valence electrons, and each oxygen (O) has 6 valence electrons, giving a total of 16 (4 from carbon and 12 from the two oxygens). In the structure, carbon is the central atom with double bonds to each oxygen atom, completing the octet for all atoms: \[O=C=O\]Each line represents a pair of shared electrons.

Solubility of CO extsubscript{2} in Seawater

Carbon dioxide is soluble in seawater, but its solubility is limited compared to other gases like ammonia or hydrogen chloride. When CO extsubscript{2} dissolves in water, it forms carbonic acid (H extsubscript{2}CO extsubscript{3}), which contributes to ocean acidification. The solubility of CO extsubscript{2} is influenced by temperature and pressure, with colder water being more capable of dissolving higher amounts of CO extsubscript{2}.

Key concepts

Atmospheric Concentration of Carbon Dioxide

The atmospheric concentration of carbon dioxide is a key parameter for understanding our planet's climate. It is typically measured in parts per million (ppm), which indicates the number of carbon dioxide molecules per million air molecules. A current average concentration is around 415 ppm. This number is not static; it can vary depending on factors such as location and season.
Natural processes, like the photosynthesis of plants, help regulate these levels by absorbing carbon dioxide, but human influences are more dominant today in driving its increase. Higher atmospheric carbon dioxide concentrations enhance the greenhouse effect, leading to a warming planet and numerous climatic changes.

• Measured in parts per million (ppm)
• Approximately 415 ppm in recent times
• Variations due to natural processes like seasonal plant growth

Fossil Fuel Combustion and CO2 Increase

Fossil fuel combustion is the main human activity that boosts atmospheric carbon dioxide levels. Burning coal, oil, and natural gas releases large amounts of CO2. These fuels undergo chemical reactions in which carbon bonds break, combining with oxygen to produce energy, and form carbon dioxide as a byproduct.
Deforestation compounds this issue by reducing the number of trees, which are natural CO2 absorbers. With fewer trees, more carbon dioxide remains in the atmosphere, contributing further to global warming and climate change.

• Primary source of CO2 emissions
• Combustion of coal, oil, and natural gas is key
• Deforestation reduces CO2 absorption

Lewis Structure of CO2

Understanding the Lewis structure of carbon dioxide is fundamental for recognizing how atoms connect in molecules. To plot this structure, we first determine the total valence electrons, which are available for bonding. Carbon has four valence electrons, while each oxygen atom has six, summing up to sixteen electrons.
In the CO2 molecule, carbon acts as the central atom with double bonds extending to each oxygen atom, depicted as: \[ O=C=O \] The double line represents two pairs of shared electrons, satisfying the octet rule for all involved atoms. This rule states that atoms are more stable when they have eight electrons in their outer shell, similar to noble gases.

• Carbon as central atom
• Double bonds with each oxygen
• Sixteen valence electrons in total

Ocean Solubility of Carbon Dioxide

Carbon dioxide is soluble in seawater, but its solubility is not as high as other gases like ammonia. When CO2 dissolves, it reacts with water to form carbonic acid (H2CO3), which contributes to ocean acidification—a pressing environmental issue threatening marine life.
The solubility of carbon dioxide in water increases with colder temperatures and higher pressures, meaning that deeper and colder ocean regions can absorb more carbon dioxide. However, the increase in atmospheric CO2 is overwhelming the oceans' ability to absorb it, leading to adverse effects such as decreased pH levels.

• Forms carbonic acid in water
• Greater solubility in colder water
• Leads to ocean acidification