# Depth of Water and Energy Required to Boil

• tempuser1
In summary, the boiling of water in a deep pot will take more energy than boiling water in a shallow pot, but it will boil off the water in the deep pot faster because the heat loss by convection is greater.
tempuser1
I have been out of college for more than 20 years and my basic physics knowledge has become quite rusty. Someone made a statement today related to making maple syrup. They stated the energy required to boil a pan of sap 2' wide x 3' long x 6" deep was the same as the energy required to boil 1" of sap in the same pan. Am I correct in thinking the energy required to boil the shallower sap would be less? Wouldn't it take more energy for the air bubbles to pass through a deeper column of sap? Thanks for the input! -John

I suppose your friends meant the amount of energy per volume of sap, and they did not mean it would take the same energy to boil off six times as much sap.

The bulk of the energy needed, is to evaporate the water in the sap, and that will be the same for a shallow pan and for a deep pan, however:
A deep pan will leak more heat through the environment through the sides.

The energy lost by the bubbles isn't a factor, because any friction would be converted to heat, but when the syrup becomes thick, overheating the bottom of a deep pan
becomes a problem, because heat loss by convection becomes harder, and it also becomes harder for the steam bubbles to get out of the area.
To prevent this you need to reduce the heat, and the heat available for evaportation wil then become less, while the heat lost to the air around the pan will remain the same, because the pan is still at boiling temperature.

tempuser1 said:
I have been out of college for more than 20 years and my basic physics knowledge has become quite rusty. Someone made a statement today related to making maple syrup. They stated the energy required to boil a pan of sap 2' wide x 3' long x 6" deep was the same as the energy required to boil 1" of sap in the same pan. Am I correct in thinking the energy required to boil the shallower sap would be less? Wouldn't it take more energy for the air bubbles to pass through a deeper column of sap? Thanks for the input! -John

It's true that, boiling water in a higher pressure requires more energy. But, to my knowledge, the heat in the bottom causes convection currents of water and brings heated water to the surface. I haven't seen it, but i think the water bubbles in the surface finally not at the button, unless the heating rate is so much that the convection currents can't transfer it effectively. Industrial boilers are made of an upper thank connected to a lower tank via two bunches of tubes one on each sides. They form loops of water current. The flame heats the pipes on one side more than the other side, this makes the water to go up via tubes on the more heated side and return back to the lower tank via the less heated side. The circulation is continuous and the evaporation takes place in the upper thank because the pressure is lower there.

## 1. What is the relationship between the depth of water and the energy required to boil?

The depth of water and the energy required to boil are directly proportional. This means that as the depth of water increases, the energy required to boil also increases. This is because the deeper the water, the more water molecules there are to heat up, requiring more energy to reach the boiling point.

## 2. Does the type of container affect the depth of water and energy required to boil?

Yes, the type of container can affect the depth of water and energy required to boil. Different materials have different thermal conductivities, meaning they transfer heat at different rates. A container with high thermal conductivity will require less energy to heat up the water to boiling compared to a container with low thermal conductivity.

## 3. How does atmospheric pressure affect the depth of water and energy required to boil?

Atmospheric pressure has a significant impact on the depth of water and energy required to boil. As atmospheric pressure decreases, the boiling point of water also decreases. This means that at higher elevations, where atmospheric pressure is lower, water will boil at a lower temperature and require less energy to reach that temperature.

## 4. Is the depth of water and energy required to boil affected by impurities in the water?

Yes, impurities in water can affect the depth of water and energy required to boil. Impurities such as salt or other minerals can raise the boiling point of water, meaning it will take more energy to reach the boiling temperature. This is why it takes longer to boil saltwater compared to freshwater.

## 5. Can the depth of water and energy required to boil be calculated?

Yes, the depth of water and energy required to boil can be calculated using the specific heat capacity of water and the heat of vaporization. Specific heat capacity is the amount of energy needed to raise the temperature of a substance by 1 degree Celsius, and the heat of vaporization is the amount of energy needed to change a liquid into a gas. By using these values, the depth of water and energy required to boil can be determined using the formula Q = m x c x ΔT + m x H, where Q is the energy required, m is the mass of water, c is the specific heat capacity, ΔT is the change in temperature, and H is the heat of vaporization.

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