Does the temperature fluctuate slowly when water is heated?

By Don Lincoln, PhD, Fermila National Emergency Laboratory (Fermilab)

There is a lot of misconception about how subtle heating elements work around the tropics. How do you feel about putting a pot of water on the fire and constantly warming it up to a constant temperature? Does this sound reasonable to you? Let’s find out.

It takes 2030 units of energy to boil water, which is more than double the amount of energy it takes to melt ice and bring it to boiling temperature. (Image: New Africa / Shutterstock)

Temperature change is never linear

Suppose you took a pound of ice and put it in a very strong, sealed metal container and began to heat it. To monitor what is happening, insert the thermometer into the ice before cooling. To make the test easier to translate, insert the same amount of energy into the container every minute. In other words, they put the container on a beautiful, continuous flame.

Suppose you remove ice from a standard refrigerator at -20 degrees Celsius or 0 degrees Fahrenheit. And then heat it up to 120 ° C, or just 250 degrees Fahrenheit.

Many people think that as the power increases, the temperature of the ice, then the water, then the steam, changes constantly. The following graph shows what most people normally think.

The image starts with the temperature on the y-axis and the power units on the x-axis, with a straight diagonal line in the center, starting from the bottom left corner to the top right corner.
It is a common misconception that there is a constant change in water temperature as power increases. (Image TGCD)

It only takes 2,900 units of energy to heat ice from -20 degrees Celsius to 120 degrees Celsius. And, if you focus on the shape, it’s just a straight line – a constant temperature change as power increases. However, this does not really happen when you do the experiment.

If you increase it slowly and continuously by about 2900 units, you will see the temperature rise, and then stay constant at 0 ° C, then rise again, then stay at 100 ° C, then rise again.

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Boiling water requires doubling its energy input rather than melting ice

32 ° and 212 ° Fahrenheit 0 ° and 100 ° C are the cooling and boiling temperatures of the water.

The following graph shows that you can heat the ice by increasing the power. But then it stays on the ice for a long time without changing the temperature. It takes 42 units of energy to heat the ice from -20 ° to 0 ° C. It then takes 334 units of energy to melt the ice.

Once the ice has turned into water, you can easily heat the water. It takes 420 units of power to bring the temperature from 0 ° C to 100 ° C. That is more powerful than melting ice into water.

Graph image with the temperature on the y-axis and the thermal force on the x-axis, and the line starting at the bottom left corner, rises to zero degrees Celsius, then rises to 100 degrees Celsius, and finally to 120 degrees Celsius It grows and ends.
If you increase the power slowly and steadily, the temperature rises, then it stays constant for a while, then it goes out again, then it stays constant again, then it rises again. (Image TGCD)

The most exciting thing is when the water reaches 100 ° C. You can see in the graph that the temperature stays there for a long time. You have to put a lot of energy into boiling water and turning it into steam. In fact, it will take 2030 units of energy to produce water. That is more than double the amount of energy needed to melt the ice and bring it to a boil.

Then, when all the water is boiled and turned into steam, it becomes easier to raise the steam temperature. It only takes 40 units of energy to raise the temperature by 20 degrees Celsius.

Therefore, although it does not take much energy to change the temperature of ice or steam, it takes about twice as much energy to change the water temperature by 1 ° compared to ice and steam.

However, the largest energy pigs are in the process of melting and boiling, and especially boiling. They are, in fact, power-hungry transitions.

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Changing the water temperature requires a lot of energy

Another notable misconception, but perhaps a little known fact, is that it is very difficult to change the temperature of the water. For example, you can compare it to more common metals, such as iron.

If you take a certain amount of energy to increase the temperature of one kilogram of water by 1 ° C, that same energy will increase the temperature of the metal by 8 ° C. And it’s not just metal. It is twice as hard to heat water as alcohol. Another surprise is that asphalt is heated five times more than water.

When you go down to it, water is basically a huge sponge. It can dissipate large amounts of energy without changing the temperature. And the opposite is also true. When water changes the temperature, it becomes very difficult to absorb and cool a lot of energy.

If you live near a beach, this is why the temperature on the beach is more than 50 miles above ground level. The same sun is beating on the dirt and the water, but for each step the water takes, the temperature of the waste changes by 5 °.

And in winter, the ground cools and cools faster than the lake. So coastal winters are generally at least softer, at least warmer, than in the ground.

Challenges in thermodynamics

The study of thermodynamics has more misconceptions than many branches of physics. They know how to warm and cool things in general, but not to see the power move. It’s different when it comes to projects and the physics of cars and balls. We can see when those things happen that will help us build a better understanding of them.

However, this is not the case with heat and heat energy. For those, we need to use indirect tools. We need accurate thermometers and instruments to measure power. Although we knew a great deal about motion physics in the 1500’s and 1600’s, it was not until the 1800s and even the 20th century that thermodynamics began to unravel.

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Common questions about hot water and temperature change

Q: How much energy is needed to boil water?

He It takes 2030 units of heat energy to boil water, More than double the amount of energy needed to melt ice and bring it to a boil. So water does not boil without sufficient energy.

Q: Why does it take more energy to raise the water temperature?

Water is like a big hot sponge. It can dissipate large amounts of energy without altering the temperature. This is why water stays at that temperature for a long time after reaching 100 ° C, which is why it takes a lot of energy to boil the water and turn it into steam.

Q: What effect do large bodies of water have on heat?

Since Water acts like a heat spongeIf you live on the beach or near a large body of water, the temperature on the beach is more than 50 degrees Fahrenheit. The sun warms the earth faster than water, and The temperature of the ground changes by 5 ° for each degree that the water makes. On the other hand, during the winter, the ground cools down and cools very quickly. So beach winters are generally lighter than indoor.

Q: Does water heat up slowly or quickly?

It’s so Difficult to change the water temperature. For example, if you take a certain amount of energy to increase the temperature of one kilogram of water by 1 ° C, that same energy will increase the temperature of the metal by 8 ° C.

Keep reading
When you drink a lot of water – the dangers of overdrinking
What does water do to us? Water function
Do we really need eight glasses of water a day?

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