Problem 16 - Campbell Biology Concepts & Connections

Question

In agricultural areas, farmers pay close attention to the weather forecast. Right before a predicted overnight freeze, farmers spray water on crops to protect the plants. Use the properties of water to explain how this method works. Be sure to mention why hydrogen bonds are responsible for this phenomenon.

Step-by-Step Solution

Answer

Spraying water uses water's high specific heat and heat release upon freezing to protect crops from overnight freeze, thanks to hydrogen bonds.

Step 1 - Introduction to the Problem

Understand that farmers spray water on crops to protect them from overnight freeze. This method relies on the properties of water and the role of hydrogen bonds.

Step 2 - Understand the Properties of Water

Water has a high specific heat capacity, meaning it can absorb a lot of heat without a significant change in temperature. This property maintains a more stable temperature around the crops.

Step 3 - The Role of Hydrogen Bonds

Hydrogen bonds are the attractions between the slightly positive hydrogen atoms and slightly negative oxygen atoms in water molecules. These bonds require a lot of energy to break, contributing to water's high specific heat capacity.

Step 4 - Freezing Process

When water turns into ice, it releases latent heat. This release of heat provides warmth to the surrounding environment, preventing the crops from freezing.

Step 5 - Conclusion and Restatement

By spraying water, farmers utilize the high specific heat capacity and the heat release during the freezing process to protect crops. The hydrogen bonds in water are essential in this temperature regulation.

Key Concepts

Hydrogen Bonds

Hydrogen bonds play a crucial role in water's unique properties. These bonds form between the slightly positive hydrogen atoms and slightly negative oxygen atoms in water molecules.

When water molecules come together, the hydrogen bonds help hold them in place. This bonding requires a lot of energy to break. This means that water can absorb a lot of heat without changing temperature drastically.

This is important for farmers because it helps keep the temperature stable around crops. By spraying water, they take advantage of these hydrogen bonds. As the temperatures drop, these bonds help manage and stabilize heat.

Specific Heat Capacity

Specific heat capacity is the amount of heat required to change the temperature of a substance. Water has a high specific heat capacity.

This means that water can absorb a lot of heat without a significant change in temperature. When farmers spray water on plants, it acts as a buffer against rapid temperature drops. The water absorbs heat from the air and plants during the day. At night, this stored heat helps to maintain a more consistent temperature around the crops.

The high specific heat capacity is beneficial in stabilizing the environment, protecting plants from sudden freezes.

Latent Heat

Latent heat is the energy released or absorbed during a phase change, without changing the temperature. When water turns into ice, it releases latent heat. This process can be vital in protecting crops from cold weather.

During a freeze, when farmers spray water, the water begins to freeze and releases latent heat. This heat warms the surrounding air and prevents the crops from freezing.

This release of energy during the freezing process is another way water helps to regulate temperature. By spraying water, farmers make use of this property to shield their crops from overnight frost.