Question

The density of water at \(4.00^{\circ} \mathrm{C}\) is \(1.00 \mathrm{~g} / \mathrm{mL}\). The density of ice at \(0{ }^{\circ} \mathrm{C}\) is \(0.917 \mathrm{~g} / \mathrm{mL}\). Water is different from most other substances in that the solid phase (ice) is less dense than the liquid phase. Explain why this characteristic makes ice fishing possible.

Short answer

In conclusion, ice fishing is possible because ice has a lower density than water, causing it to float on the surface of a body of water. This floating ice layer creates an insulative barrier that helps maintain a stable temperature in the liquid water below and provides a solid platform for anglers to access the water beneath the ice.

Step-by-step solution

Understanding the density of ice and water

First, we need to understand the given information. The density of water at 4.00°C is 1.00 g/mL, and the density of ice at 0°C is 0.917 g/mL. This indicates that ice is less dense than water.

Density and buoyancy

Objects will float in a fluid (like a liquid or gas) if their density is less than the fluid's density. This is due to buoyancy, an upward force exerted by the fluid that opposes the weight of an object submerged in it. The buoyant force is determined by the fluid's density and the volume of fluid displaced by the object (Archimedes' principle).

Floating ice

Since ice has a lower density than water, when it forms on the surface of a body of water, it will float. This floating layer of ice creates an insulating barrier between the cold air above and the liquid water below, helping to prevent the water from freezing completely.

Ice fishing

Now that we understand why ice floats on water, we can explain how this characteristic makes ice fishing possible. Ice fishing involves drilling a hole through the ice layer, allowing a person to fish in the unfrozen water below. The floating ice layer provides a stable platform to stand on and access the water beneath, while the insulating barrier provides a more stable temperature in the liquid water below, allowing fish to survive in the colder months. In conclusion, the lower density of ice compared to water enables it to float on the surface of a body of water, creating an insulating barrier that allows fish to survive below and provides a stable platform for ice fishing.

Key concepts

Buoyancy

Buoyancy is the force that allows objects to float or sink in a fluid. This happens because every fluid exerts an upward force on objects submerged in it. This force is known as the buoyant force. The principle behind buoyancy states that an object placed in a fluid will experience an upward force equal to the weight of the fluid volume displaced by the object.

In essence, if the buoyant force is greater than the object's weight, the object will float. If it's less, the object will sink. In the context of ice and water, the buoyant force is what keeps the ice floating on water. Since ice is less dense than water, the weight of water displaced by the submerged part of the ice is greater than the weight of the ice itself, hence it floats. This is why icebergs are visible above the surface of the water.

Archimedes' principle

Archimedes' principle is a fundamental concept that helps explain why objects float or sink. It states that the buoyant force acting on a submerged object is equal to the weight of the fluid that the object displaces. This means that when an object is placed in a fluid, if the weight of the fluid it pushes aside is more than the weight of the object itself, the object will float. If it is less, the object will sink.

This principle is key to understanding why ice floats on water. Given that ice has a density of 0.917 g/mL and water has a higher density of 1.00 g/mL, ice displaces water's weight amounting to more than its own weight. Therefore, it experiences a net upward buoyant force, which is why it stays afloat. This principle also helps explain many natural phenomena and is used in designing ships and submarines.

Ice fishing

Ice fishing is an activity made possible by the unique properties of water and ice. When the surface water in a lake or river freezes to form ice, the lower density of ice compared to liquid water means it floats, creating a solid surface while the water below remains unfrozen.

The floating ice insulates the water underneath, protecting it from freezing even deeper and allowing aquatic life, such as fish, to survive during cold months. Ice fishing enthusiasts take advantage of this phenomenon by drilling holes through the ice to reach the liquid water, where they can catch fish.

The stability of the ice layer provides a reliable platform for fishing gear and anglers. This stable surface is critical for ensuring safety and comfort during the activity. By understanding the principles of buoyancy and the densities of water and ice, ice fishing becomes not just feasible, but an exciting winter pastime.