Pathway to High P and T from Very Low P and T

In summary, the conversation discusses the process of taking a block of ice from low pressure and temperature to high pressure and temperature. The initial conditions are at a very low pressure and temperature, which is well below the triple point. The approach is to heat the ice until it hits the sublimation line, where it will convert directly to vapor. However, after this point, it becomes unclear how to quantify the path on the P-T diagram, especially with the assumption of ideal gas under constant volume. The conversation also mentions the potential kinks in the P-T diagram due to the liquid water and water vapor phases.
  • #1
neutrons
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Hi all,

There is a block of ice (say 20 cm^3) sitting inside a box (50cm^3, constant volume) at very low P and low T (say P = 10^(-8) kPa and T = 100 K ... roughly ambient moon P and T).

There is a constant heat flux incident on the box. I want a 'path-way' (explicit phase transition regimes etc) that will take this ice block to high T (~ 500 K) and high P (~ 18 MPa), and quantify energy requirement in each step. The heat source is infinite. Please make any other assumption that may prove helpful.

My approach:

The given P and T is well below the triple point. If I heat the ice, it will increase its T under the same initial P. Once it hits the sublimation line, the energy input will convert it directly to vapor (under constant P, is this assumption valid?) .

Now, after everything is vapor, if I continue heating, I am not sure how to quantify the path-way in the P-T diagram. (Assuming ideal gas under constant V... P has linear relationship with T but I can't tell anything about the slope). How does the P and T change now (after sublimation) under constant volume and constant heat source?

Please help me quantify this.

Many thanks !

(I was looking at XSteam and there is no data at low P and T.)
 
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  • #2


Not sure your system will be that well behaved.
The ice will shrink as it melts, so there will be an interval where you have liquid water and water vapor in your box. That will put a kink in your P-T diagram between 273 and 277 K, with another one at 373+ K when the water turns to steam.
 

1. What is the significance of "Pathway to High P and T from Very Low P and T"?

The concept of "Pathway to High P and T from Very Low P and T" refers to the process by which materials or substances undergo changes in pressure and temperature conditions to reach a state of high pressure and temperature. This pathway is important for understanding geological processes, such as the formation of minerals and rocks, and for studying the behavior of materials under extreme conditions.

2. How does pressure and temperature affect the pathway to high P and T?

The pathway to high P and T is driven by changes in pressure and temperature. As pressure and temperature increase, materials undergo physical and chemical changes, such as phase transitions and reactions, which can lead to the formation of new minerals or the alteration of existing ones. The specific effects of pressure and temperature on the pathway depend on the composition and properties of the materials involved.

3. What are some examples of geological processes that involve the pathway to high P and T?

The pathway to high P and T is involved in a variety of geological processes, including subduction (the process by which one tectonic plate is forced beneath another), metamorphism (the transformation of rocks due to changes in pressure and temperature), and volcanic eruptions (which release materials from the Earth's interior). It is also important for understanding the formation of diamonds, as these precious gems are created under extreme pressure and temperature conditions.

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Scientists use a variety of techniques and methods to study the pathway to high P and T. These include laboratory experiments, computer simulations, and field observations. By recreating extreme pressure and temperature conditions in the lab, scientists can observe how materials behave and undergo changes. Computer simulations also allow for the study of complex systems and processes that are difficult to replicate in the lab. Field observations, such as studying rocks and minerals in their natural environment, provide valuable insights into the pathway to high P and T.

5. Why is understanding the pathway to high P and T important?

Understanding the pathway to high P and T is crucial for many reasons. It helps us understand the Earth's history and how geological processes have shaped our planet. It also has practical applications, such as in the exploration and extraction of mineral resources, and in the development of new materials with unique properties. Additionally, studying the pathway to high P and T can provide insights into other planets and their geological processes, enhancing our understanding of the universe as a whole.

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