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

Water's thermal properties, including high specific heat and high heat of vaporization, are crucial for maintaining homeostasis in living organisms. Specific heat refers to the energy required to change the temperature of 1 gram of water by 1 degree Celsius, allowing water to resist temperature fluctuations. Heat of vaporization is the energy needed to convert liquid water to gas, influenced by hydrogen bonds. These properties enable organisms to stabilize internal conditions despite external temperature changes, highlighting water's essential role in biological systems.

Properties of Water- Thermal

In this video, we're going to begin our lesson on the thermal properties of water. To understand the thermal properties of water, we need to understand kinetic energy, which 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, and temperature is just defined as the average kinetic energy of molecules in a solution or in a sample. The key word here is "average." If a sample has a really high temperature, that means that the molecules in that sample have a high average motion. Notice that these molecules have large arrows to represent the high average motion that 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. However, temperature should not be confused with thermal energy. Temperature is the average kinetic energy, whereas thermal energy is the total kinetic energy of molecules that's transferred specifically as heat.

If we 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 because the average kinetic energy in these molecules is very high; they're moving really fast on average. However, the swimming pool is going to have a low temperature, it's going to be quite cool if you were to jump into that swimming pool, because the molecules on average have low motion.

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 in comparison to the swimming pool, which has a much larger volume. The swimming pool, because it has so many more molecules, the total energy of all these molecules adds up to be more than the energy in 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: more total energy because it has a lot more molecules. The hot coffee pot, even though on average the molecules have higher temperature and more motion, has a lot lower thermal energy 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. As we move forward in this lesson, we'll talk more specifically about water's thermal properties. 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 the 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 going to 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 1g 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 water's high specific heat that we talked about in our previous lesson video, water also has a high heat of vaporization. And so vaporization or evaporation is really just referring to the phase transition from a liquid state to a gaseous state, or in other words, the phase transition from a liquid to a gas. Now, the heat of vaporization is a term referring to the amount of heat required to convert exactly 1 gram of liquid to a gaseous state. Now, once again, water has a relatively high heat of vaporization, which means that it takes quite a lot of energy to convert 1 gram of liquid water into a gaseous state. And the reason that water has such a high heat of vaporization is due to the abundance of hydrogen bonds that form in the liquid state of water. So if we take a look at our image down below, we can get a better understanding of this heat of vaporization. So notice in this image we're showing you a pot of boiling water where the liquid water is being converted into a gaseous state. And so when we zoom into the liquid water and look at the water molecules here, notice that between each of these water molecules, there are an abundance of hydrogen bonds forming between them. And so there are lots and lots of hydrogen bonds in the liquid state of water. However, if we apply high amounts of energy and high amounts of heat, like what this fire beneath this pot is doing, then each of these hydrogen bonds between the water molecules can be broken. And when these hydrogen bonds are broken, the water molecules are able to escape from the liquid water into its gaseous form. And so that's what we're showing you above is a zoom in into the steam and the water vapor. And so notice that there are no hydrogen bonds between the water molecules in this steam or gaseous form. So once again, water has a high heat of vaporization which means it takes a lot of energy to convert liquid water into its gaseous form. And many of you may be familiar with this idea in your own, perhaps, for making pasta. When you put the pot of water initially onto the stove, the water does not boil immediately. In fact, it takes quite a lot of time, a lot of heat, and a lot of energy to convert the liquid water into the gaseous state, and so the fact that it takes a lot of energy is why water has a high heat of vaporization. And so this here concludes our brief lesson on water's high heat of vaporization, and we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.

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 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 the molecules in a sample, transferred as heat. For example, a hot coffee pot has a high temperature because its molecules move quickly on average, but it has lower thermal energy compared to a large swimming pool, which has more molecules overall, even though they move more slowly on average.

Why does water have a high specific heat?

Water has a high specific heat because it requires a significant amount of energy to raise or lower the temperature of 1 gram of water by 1°C. This property is due to the hydrogen bonds between water molecules, which absorb and release heat energy slowly. This high specific heat allows water to resist temperature changes, which is crucial for maintaining stable environmental and cellular conditions, supporting life processes and homeostasis.

How does water's high heat of vaporization affect living organisms?

Water's high heat of vaporization means it takes a lot of energy to convert liquid water into gas. This property is due to the numerous hydrogen bonds that need to be broken during the phase transition. For living organisms, this helps in cooling mechanisms like sweating and transpiration, where the evaporation of water from the surface removes excess heat, thereby regulating body temperature and preventing overheating.

What role does water's high specific heat play in climate regulation?

Water's high specific heat plays a crucial role in climate regulation by moderating temperature fluctuations. Large bodies of water, like oceans and lakes, absorb and store large amounts of heat energy during the day and release it slowly at night. This buffering effect helps to stabilize coastal climates, making them milder compared to inland areas. This property also supports marine life by maintaining relatively stable temperatures in aquatic environments.

How does water's thermal property support cellular functions?

Water's thermal properties, including high specific heat and heat of vaporization, support cellular functions by maintaining stable internal temperatures. Cells are composed largely of water, which helps them resist rapid temperature changes despite external fluctuations. This stability is essential for enzymatic activities and biochemical reactions that are temperature-sensitive, ensuring that cellular processes proceed efficiently and effectively.