Examples of Gas Dissolved in Liquid: Everyday & Scientific Cases

When you open a carbonated drink, the fizz you hear and see is a direct example of gas dissolved in liquid. Carbon dioxide gas is forced into the water under pressure, and when you release that pressure by opening the bottle, the gas escapes as bubbles. This is just one common case. Other examples include oxygen in the blood of fish, ammonia in household cleaners, and hydrogen chloride in hydrochloric acid. In each case, the gas molecules are mixed evenly throughout the liquid, forming a solution.

Carbonated Beverages and Pressure

The most familiar example is carbon dioxide dissolved in water to make soda, beer, or sparkling water. This process relies on Henry’s law: the amount of gas that dissolves in a liquid is proportional to the partial pressure of that gas above the liquid. At a bottling plant, carbon dioxide is pumped into the liquid at high pressure. The gas molecules are forced into the spaces between water molecules.

When you open the container, the pressure drops to atmospheric level. The solubility of carbon dioxide decreases sharply, and the gas comes out of solution, forming bubbles. The nucleation sites for these bubbles are often tiny scratches or particles inside the container. This is why a freshly poured soda fizzes more vigorously than one that has been sitting for a while.

Temperature also affects gas solubility. Carbon dioxide dissolves more easily in cold liquids than in warm ones. A warm soda goes flat faster because the gas molecules have more kinetic energy and escape the liquid more readily. The same temperature effect is seen in other gases. For example, oxygen is more soluble in cold water than in warm water, which is relevant for aquatic life.

Oxygen in Water and Aquatic Life

Fish and other aquatic organisms depend on oxygen dissolved in water. Unlike carbon dioxide in soda, oxygen is not forced into water under pressure. Instead, it enters from the atmosphere at the water’s surface or is produced by aquatic plants through photosynthesis. The concentration of dissolved oxygen in natural water is relatively low, typically between 5 and 10 parts per million (ppm) in healthy freshwater systems Royal Society of Chemistry. This is far less than the carbon dioxide in a soda, but it is enough to support respiration.

Fish extract this oxygen through their gills. Water flows over the gill membranes, and oxygen diffuses into the bloodstream because the concentration of oxygen in the water is higher than in the blood. The gills are highly efficient, capable of extracting most of the dissolved oxygen from the water passing over them. In polluted or warm water, the dissolved oxygen level can drop below 2 ppm, which can stress or kill fish.

Gases in Industrial and Household Liquids

Many industrial processes and household products rely on gases dissolved in liquids. Ammonia gas (NH₃) is highly soluble in water. Household ammonia cleaner is a solution of ammonia gas dissolved in water, typically at a concentration of 5 to 10%. The gas molecules form weak bonds with water molecules, creating ammonium hydroxide. This solution is alkaline and effective for cleaning grease and glass. The strong smell of ammonia cleaner comes from the gas escaping the solution.

Another important example is hydrogen chloride gas (HCl) dissolved in water to form hydrochloric acid. This is a much stronger acid than ammonia solution. Concentrated hydrochloric acid used in laboratories is about 37% HCl by weight. The gas dissolves so readily that it creates a fuming, corrosive liquid. In industry, this acid is used for steel pickling, oil well acidizing, and food processing.

Gases in Blood and Human Physiology

Human blood carries several dissolved gases that are essential for life. Oxygen is the most critical. It enters the blood in the lungs, where the partial pressure of oxygen in the alveoli is higher than in the incoming blood. Oxygen molecules diffuse across the thin alveolar membrane and dissolve directly into the blood plasma. Most of that oxygen then binds to hemoglobin in red blood cells, but a small fraction remains physically dissolved in the plasma. This dissolved portion is what actually drives diffusion into tissues.

Carbon dioxide is transported in the blood in three forms. Some is simply dissolved in plasma. Some binds directly to hemoglobin. The rest is converted into bicarbonate ions through a reaction catalyzed by the enzyme carbonic anhydrase. This conversion is reversible. In the lungs, bicarbonate is turned back into carbon dioxide gas, which is exhaled. Nitrogen gas is also dissolved in blood, but it is inert and does not participate in metabolism.

Scuba divers face a risk related to dissolved nitrogen. Under high pressure at depth, nitrogen gas dissolves in the blood and tissues at higher concentrations than at the surface. If a diver ascends too quickly, the pressure drops rapidly, and the nitrogen comes out of solution, forming bubbles in the blood and joints. This causes decompression sickness. Treatment involves recompression in a hyperbaric chamber, which forces the nitrogen bubbles back into solution so they can be eliminated slowly.

Key Takeaways

• Many common products, from soda to cleaning solutions, are examples of gas dissolved in liquid.
• Henry’s law describes how gas solubility depends on pressure and temperature.
• Dissolved oxygen in water is essential for fish and is a key measure of water quality.
• Industrial gases like ammonia and hydrogen chloride are stored and used as aqueous solutions.
• Human blood carries dissolved oxygen, carbon dioxide, and nitrogen, each with different transport mechanisms.
• Rapid ascent from deep water can cause dissolved nitrogen to form bubbles, leading to decompression sickness.