Question

Which property of \(\mathrm{CO}_{2}\) makes it of biological and geo-chemical importance? (a) Its acidic nature. (b) Its colourless and odourless nature. (c) Its low solubility in water. (d) Its high compressibility.

Short answer

Its solubility in water makes \textrm{CO}_2 biologically and geochemically important because it enables involvement in chemical reactions and biological processes.

Step-by-step solution

Identify the Key Properties of \textrm{CO}_2

Look at each property mentioned in the options and consider their relevance to biology and geochemistry. Carbon dioxide is known to be involved in several biological processes such as photosynthesis, respiration, and as a greenhouse gas affecting climate. Also, assess its physical properties and their implications in geochemical cycles.

Evaluate the Biological and Geochemical Significance

Carbon dioxide's acidic nature allows it to participate in buffering systems in blood and water, which is biologically significant. Although colourless and odourless, this fact does not inherently affect biological and geochemical importance. Its solubility in water is crucial because it enables carbon dioxide to be carried in blood and to participate in the carbonic acid-bicarbonate buffer system in the ocean, a cornerstone of marine geochemistry. The high compressibility of CO2 might be more relevant to its physical storage or industrial applications rather than its role in biological systems or geochemistry.

Select the Most Appropriate Option

Given the importance of CO2 in biological processes like photosynthesis and respiration, and its role in the acid-base balance in the environment, the property that makes it biologically and geochemically important is its solubility in water, as this allows it to be readily involved in chemical and biological reactions.

Key concepts

Acidic Nature of Carbon Dioxide

Carbon dioxide (\text{CO}\(_2\)) exhibits an acidic property when it dissolves in water, forming carbonic acid (\text{H}\(_2\)\text{CO}\(_3\)). This reaction is pivotal in both environmental science and physiology. In the human body, \text{CO}\(_2\) helps maintain the pH balance of blood through the bicarbonate buffering system, which is essential for sustaining life. Changes in blood \text{CO}\(_2\) levels can lead to respiratory acidosis or alkalosis, reflecting the significance of its acidic nature.

Similarly, in aquatic ecosystems, \text{CO}\(_2\)'s conversion to carbonic acid can affect the acidity of water bodies, which influences the survival of marine organisms and the solubility of nutrients. Thus, the acidic nature of \text{CO}\(_2\) is fundamental to understanding its role in biological and environmental systems.

Solubility in Water

The solubility of carbon dioxide in water is a critical property that facilitates many of its roles in the environment. It allows \text{CO}\(_2\) to be transported in the blood as bicarbonate (\text{HCO}\(_3^{-}\)), a key component in cellular respiration and photosynthesis. The ability of \text{CO}\(_2\) to dissolve in water enables aquatic plants to absorb it for photosynthesis, providing the foundational energy source for marine food webs.

In the atmosphere, \text{CO}\(_2\) dissolves into the ocean's surface water, contributing to carbonate rock formation over geological timescales through processes such as calcium carbonate precipitation. The exchange of \text{CO}\(_2\) between the atmosphere and the ocean is also vital for regulating Earth's temperature, highlighting the importance of its solubility in water.

Carbon Dioxide in Biological Processes

Carbon dioxide plays an essential role in the Earth's biological processes. In photosynthesis, plants convert \text{CO}\(_2\) and water into glucose and oxygen, fundamentally supporting life by producing food and oxygen. During cellular respiration, organisms reverse this process, consuming oxygen to break down glucose for energy and emitting \text{CO}\(_2\) as a byproduct.

As an intermediary in the carbon cycle, \text{CO}\(_2\) also affects the growth and survival of autotrophs and heterotrophs alike, acting as a substrate for photosynthesis and a product of respiration. The delicate balance maintained by \text{CO}\(_2\) in biological processes is crucial for the stability of ecosystems globally.

Geochemical Significance of CO2

Carbon dioxide holds remarkable geochemical significance. Its exchange between the atmosphere, oceans, and land through various chemical reactions shapes Earth's climate and evolution. \text{CO}\(_2\) acts as a greenhouse gas trapping heat in the atmosphere, influencing global temperature and climate patterns. Its dissolution and reaction with minerals lead to the formation of carbonates, which are vital in sedimentary rock formation and carbon sequestration.

Furthermore, \text{CO}\(_2\) is a key player in the long-term carbon cycle, a natural thermostat for Earth's climate. The weathering of rocks, volcanic activity, and the burning of fossil fuels all involve the release or absorption of \text{CO}\(_2\), making its geochemical roles diverse and impactful on a planetary scale.