Properties of Water- Thermal - Online Tutor, Practice Problems & Exam Prep

Water's thermal properties are crucial for life, characterized by high specific heat and high heat of vaporization. Specific heat refers to the energy needed to change the temperature of 1 gram of water by 1°C, allowing water to resist temperature fluctuations. Heat of vaporization is the energy required to convert liquid water to gas, influenced by hydrogen bonds. These properties help maintain homeostasis in organisms, ensuring stable internal conditions despite external temperature changes.

Properties of Water- Thermal

In this video, we're going to begin our lesson on the thermal properties of water. And so to understand the thermal properties of water, we need to understand kinetic energy. Kinetic energy is really just a measure of energy in the form of motion. If substances are moving, that means that they have kinetic energy. It's really the energy of motion. Now, temperature is a term that we've all heard before in our past, and temperature is just defined as the average kinetic energy of molecules in a solution or in a sample. The average here is really the key word. If a sample has a really, really high temperature, that means that the molecules in that sample have a high average motion. Notice that these molecules in this sample have large arrows to represent the high average motion they have. They're moving around a lot and very fast. Now, low temperature, on the other hand, means that the molecules in that sample have low average motion. Notice that these molecules have small arrows to represent that they're moving very slowly in comparison to the high-temperature samples.

Temperature is not to be confused with thermal energy. Temperature is the average kinetic energy. However, thermal energy is the total kinetic energy of molecules that's transferred specifically as heat. If we take a look at our image down below, on the right-hand side we can distinguish between temperature and thermal energy. Notice that we're comparing two samples, a hot coffee pot on the left-hand side with a large swimming pool on the right-hand side. The hot coffee pot, if we measure its temperature, is going to be quite high. It's going to have a high temperature because the average kinetic energy of these molecules is really high. They're moving really fast on average. The swimming pool, however, is going to have low temperature. It's going to be quite cool if you were to jump into that swimming pool, and that's because the molecules, on average, have low temperature. However, if we focus on the thermal energy, what we'll find is that the hot coffee pot, because it has such a small volume, actually has a lower thermal energy compared to the swimming pool which has a much larger volume. The swimming pool has so many more molecules, and the total energy of all these molecules adds up to be more energy than the molecules in the hot coffee pot. That means that the swimming pool, simply because it has a much larger volume, has higher thermal energy. There's more total energy in the swimming pool because it has a lot more molecules. The hot coffee pot, even though on average they have higher temperature, more motion, there's a lot lower thermal energy in the hot coffee pot because it has such a small volume in comparison to this large swimming pool. This concludes our introduction to kinetic energy, temperature, and thermal energy and as we move forward in this lesson, we'll talk more specifically about water's thermal property. So, I'll see you all in our next video.

Water’s High Specific Heat

In this video, we're going to introduce water's high specific heat. And so water's high specific heat really is what allows it to resist temperature changes. Now specific heat is really just defined as the amount of heat energy that's required to either raise or lower one gram of water, just one degree Celsius. And so because water has a high specific heat it means that it takes a relatively high amount of heat in order to either raise or lower 1 gram of water just 1 degree Celsius. And so think about it if you've ever tried to make some pasta first you have to put water into a pot and then you have to put that water in the pot onto a stove. But the water doesn't start boiling immediately once you put that water onto the hot stove. It takes some time. It takes quite a lot of energy in order to heat up that water and raise its temperature. And so this is water's ability to have a high specific heat and resist temperature changes. And it also works in the opposite way in terms of lowering the temperature of water. It takes a lot to lower the temperature of water. So if you have a water bottle for instance and you throw it into the freezer it doesn't freeze immediately it takes several hours in order to cool down water, until it freezes. And so water has this incredible ability to resist temperature changes because it has such a high specific heat. Now, resisting temperature changes is really, really critical for life to maintain homeostasis. Because once again, the temperatures of the environment are constantly going to be changing, some days it'll be hot, other days it'll be really cold. And so life needs to have this ability to maintain homeostasis, maintain an internal set of conditions. And because the cells are made up of a lot of water, they are able to resist the temperature changes and maintain constant temperatures inside the cell despite the fact that the outside of the cell is constantly changing. And so down below we're showing you an example of water's high specific heat. So notice we have this beaker here that's filled up with water and we're applying some heat here, a flame to the water to heat it up. But notice that the water here isn't really impressed by the amount of heat and it's saying, is that all you got? Bring on the heat. It's gonna take a lot more heat to, raise my temperature than just a little flame here. And so that is just this idea that water has a high specific heat, it takes a lot of energy to raise or lower 1 gram of water 1 degree Celsius and that is what allows water to resist temperature changes. And so this here concludes our introduction to water's high specific heat and we'll be able to get some practice applying these concepts moving forward in our course. So I'll see you all in our next video.

Which of the following is due to the high specific heat of water?

a) Oil does not mix with water.

b) A lake heats up more slowly than the surrounding environment.

c) The high surface tension of water.

d) Sugar dissolves in hot tea faster than in iced tea.

• A. Oil does not mix with water.
• B. A lake heats up more slowly than the surrounding environment.
• C. The high surface tension of water.
• D. Sugar dissolves in hot tea faster than in iced tea.

Water’s High Heat of Vaporization

So in addition to having a high specific heat, water also has a high heat of vaporization. Now vaporization is also referred to as evaporation, and so vaporization or evaporation is really just referring to the phase transition when a substance goes from a liquid state to a gaseous state or essentially when a substance is going to be converted from its liquid state to a gas state. And so the heat of vaporization is specifically defined as the amount of heat energy that's required to convert 1 gram of liquid into its gaseous state. Now, once again, water has a really high heat of vaporization, which means that it takes a relatively large amount of energy to convert 1 gram of liquid water into its gaseous state. And so the reason that water has such a high heat of vaporization is due to the abundance of hydrogen bonds that form between the water molecules in its liquid form.

And so if we take a look at our example image down below of water's heat of vaporization, notice that we're showing you the heat of vaporization of water. And so notice that we have a pot here that's filled with boiling water since we're applying a lot of heat energy to it. And so we zoom into this boiling water down below here, we can see that it's going to be in its liquid water form, which we know is going to be highly dense, compact, and it's going to be forming hydrogen bonds between different water molecules. And so you can see the H bonds or the hydrogen bonds are forming when water's in its liquid state.

Now if we want to convert liquid water into the gaseous form, water vapor, then we need to apply a high amount of energy and heat, and that's exactly what this flame is doing here. And so when we do that we're capable of breaking all of the hydrogen bonds that form between the liquid water molecules, and when we break all of those hydrogen bonds the water molecules are capable of escaping into the gaseous form, the water vapor form. And notice that the water vapor is much less dense. These water molecules are much more spread apart, and there are no hydrogen bonds, no H bonds forming between the water molecules in the water vapor form, the gaseous form. And so when, you can see that this image is just a zoom in into the steam here that's above the water.

And so the main point here is that water has a high heat of vaporization, meaning it takes a large amount of energy to convert one gram of liquid water into a gaseous state and that also helps with maintaining homeostasis and making sure that water stays in its liquid form, which is critical to maintain life. And so this here concludes our introduction to water's high heat of vaporization, and we'll be able to get some practice applying these concepts in our next video. So I'll see you all there.

Which if the following defines the term evaporation?

a) The conversion of a liquid into a vapor.

b) The conversion of a solid into a vapor.

c) The conversion of a vapor into a liquid.

d) The conversion of a vapor into a solid.

• A. The conversion of a liquid into a vapor.
• B. The conversion of a solid into a vapor.
• C. The conversion of a vapor into a liquid.
• D. The conversion of a vapor into a solid.

Choose the correct statement:Liquid water ________.

a) Is less dense than ice.

b) Has a lower specific heat than most other molecules.

c) Has a higher heat of vaporization than most other molecules.

d) Is nonpolar.

• A. Is less dense than ice.
• B. Has a lower specific heat than most other molecules.
• C. Has a higher heat of vaporization than most other molecules.
• D. Is nonpolar.

Here’s what students ask on this topic:

What is the specific heat of water and why is it important?

The specific heat of water is the amount of heat energy required to raise the temperature of 1 gram of water by 1°C. This value is relatively high at approximately 4.18 J/g°C. The high specific heat of water is crucial because it allows water to resist temperature changes, which is essential for maintaining stable environmental and internal conditions in living organisms. This property helps organisms maintain homeostasis, ensuring that their internal temperatures remain constant despite external temperature fluctuations.

How does water's high heat of vaporization contribute to homeostasis?

Water's high heat of vaporization, the energy required to convert 1 gram of liquid water to gas, is due to the hydrogen bonds between water molecules. This property is essential for homeostasis because it allows water to absorb significant amounts of heat without a large increase in temperature. When organisms sweat, the evaporation of water from the skin surface removes excess heat, cooling the body and maintaining a stable internal temperature. This process is vital for regulating body temperature in various environmental conditions.

What is the difference between temperature and thermal energy?

Temperature is the average kinetic energy of molecules in a sample, indicating how fast the molecules are moving on average. Thermal energy, on the other hand, is the total kinetic energy of all molecules in a sample, transferred as heat. For example, a hot coffee pot has a high temperature because its molecules move rapidly, but a large swimming pool has higher thermal energy due to its greater volume and total number of molecules, even if its temperature is lower.

Why does water take a long time to boil?

Water takes a long time to boil because of its high specific heat. This means that a significant amount of heat energy is required to raise the temperature of water. When you heat water, the energy is used to increase the kinetic energy of the water molecules, but due to the high specific heat, this process is slow. Additionally, the hydrogen bonds between water molecules require extra energy to break, further delaying the boiling process.

How do hydrogen bonds affect water's thermal properties?

Hydrogen bonds significantly influence water's thermal properties. These bonds form between the hydrogen atom of one water molecule and the oxygen atom of another. Due to these bonds, water has a high specific heat and high heat of vaporization. The high specific heat means water can absorb or release large amounts of heat with minimal temperature change, aiding in temperature regulation. The high heat of vaporization requires substantial energy to convert liquid water to gas, which helps in cooling mechanisms like sweating.