Question

The flounder is able to survive in very cold water, but only when water is in its liquid state. What property of water prevents the ocean from freezing solid when the temperature in the air is well below water's freezing point?

Short answer

The property of water that prevents the ocean from freezing solid when the air temperature is below its freezing point is a combination of its high heat capacity, density change during freezing (which causes ice to float on top), and the global ocean currents. These factors work together to keep most of the ocean water in its liquid state despite freezing air temperatures.

Step-by-step solution

Identify the freezing/melting point of water

The freezing point (or melting point) of water is when the temperature is at \(0^{\circ}\text{C}\) (32°F). At this temperature, water can either be in the form of ice or in its liquid state.

Understand heat capacity

Heat capacity is the amount of heat needed to raise the temperature of a substance by \(1^{\circ}\text{C}\) (or 1 Kelvin). Water has a high heat capacity, meaning it can absorb a lot of thermal energy without significantly changing its temperature. Due to this high heat capacity, water is more resistant to temperature changes than most other substances.

Learn about water's density change during freezing

When water freezes, its physical structure forms a crystalline lattice that takes up more space and causes it to be less dense than liquid water. As a result, ice floats on top of liquid water. The floating ice acts as an insulating layer, preventing the cold air from directly cooling the water underneath and therefore preventing the lower layers of water from freezing.

Discover the role of ocean currents

Ocean currents are another factor that helps prevent the ocean from freezing solid. These currents are large-scale movements of water throughout the world's oceans that act as conveyer belts, constantly distributing heat between the warm equatorial regions and the cold polar regions. As a result, ocean water remains mostly liquid, even in colder regions.

Identify the property that prevents the ocean from freezing solid

The property of water that prevents the ocean from freezing solid even when the air temperature is below the water's freezing point is a combination of its high heat capacity, density change during freezing (which causes ice to float on top), and the global ocean currents. These factors work together to keep most of the ocean water in its liquid state despite the freezing air temperatures.

Key concepts

Heat Capacity of Water

Water has a remarkable ability to store heat, a property scientifically known as heat capacity. This means it takes a significant amount of energy to increase the temperature of a given amount of water. For instance, when you heat a pot of water on the stove, it seems to take ages for it to boil, right? That's because of water's high heat capacity. This characteristic plays a crucial role in regulating the Earth's climate and temperature. Large bodies of water, such as lakes and oceans, can absorb and store a great deal of heat during sunny days, and then slowly release it over time, helping to moderate temperature fluctuations between day and night. This affect not only makes our planet habitable by keeping extreme temperatures in check, but it also ensures that aquatic life, like the flounder mentioned in the textbook exercise, can thrive in stable conditions.

Density Change of Water

One of the most unusual and interesting properties of water is how its density changes with temperature, especially as it transitions from liquid to solid. Unlike most substances, water's density decreases when it freezes. This phenomenon is why ice floats on liquid water – think of icebergs in the ocean or ice cubes in your drink.

The crystalline structure of ice is less compact than the structure of liquid water, leading to this counterintuitive floating effect. This density anomaly has far-reaching consequences for aquatic ecosystems. It provides an insulating layer on top of bodies of water during the winter, which helps to protect the delicate marine life beneath. If water behaved like other substances and became denser upon freezing, ice would sink, leading to completely frozen water bodies that could not support life year-round.

Ocean Currents

Ocean currents are the large-scale movement of water that circulate through the world's oceans. These currents are like underwater rivers that transport warm water from the equator towards the poles and cooler water back towards the equator. They are driven by various factors including wind, the rotation of the Earth, and variations in water temperature and salinity.

Ocean currents have a profound effect on the climate and the temperature regulation of our planet. They act as a global conveyor belt, moving heat around, which plays a vital role in preventing the oceans from freezing over, especially in polar regions. These currents are also critical for marine life, distributing nutrients throughout the oceans, and affecting weather patterns across the globe.

Freezing Point of Water

The freezing point of water is known to be at 0°C (32°F). This is the temperature at which water transforms from a liquid to a solid state, forming ice. However, the freezing of water is not just a simple temperature drop. There are factors such as the presence of impurities or the application of pressure that can affect the exact temperature at which water freezes - this is why salt is often used to melt ice on roadways as it lowers the freezing point.

In the natural environment, bodies of water do not instantly turn to ice even when the air temperature falls below freezing due to the thermal inertia provided by water's high heat capacity. Moreover, the presence of a saline environment, such as the ocean, further lowers the freezing point of water, which helps to keep it in a liquid state within a wider range of temperatures, allowing marine life to survive in various conditions.