Soil vaporization value

[M3X_2.0]

We currently don't have a soil vaporization value in the Calculations page, so I calculated it myself.

Spoiler: calc

Soil is composed of multiple materials, each requiring different amounts of energy to vaporize. The composition used is: 40% SiO2 (quartz), 20% feldspar, 15% kaolinite (clay mineral), 5% hematite (iron oxide), 15% water and organic matter, and 5% air (ignored).

• Soil density: 2.7 g/cm3 (0.0027 kg/cm3)
• Starting temperature: 20C

Sources:

• Soil density and specific heat: https://www.engineeringtoolbox.com/specific-heat-capacity-d_391.html
• SiO2 latent heat of vaporization (11,770 kJ/kg) and boiling point (3177 K / 2904C): https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012JE004082

SiO2 (40% of soil mass):

• Specific heat: 730 J/kg*K
• Heating to melting point (1710C): 730 x (1710-20) = 1,233,700 J/kg
• Latent heat of fusion: 50,000 J/kg
• Heating from melting to boiling (2904-1710 = 1194C): 730 x 1194 = 871,620 J/kg
• Latent heat of vaporization: 11,770,000 J/kg
• Total SiO2: 13,925,320 J/kg

Feldspar (20% of soil mass):

• Specific heat: 750 J/kg*K
• Heating to melting point (1220C): 750 x (1220-20) = 900,000 J/kg
• Latent heat of fusion: 100,000 J/kg
• Heating from melting to boiling (3500-1220 = 2280C): 750 x 2280 = 1,710,000 J/kg
• Latent heat of vaporization: 6,000,000 J/kg (estimated, experimental data scarce)
• Total feldspar: 8,710,000 J/kg

Kaolinite (15% of soil mass):

• Specific heat: 800 J/kg*K
• Heating to decomposition/vaporization (~3000C): 800 x (3000-20) = 2,384,000 J/kg
• Latent heat of fusion + vaporization: 5,200,000 J/kg (estimated)
• Total kaolinite: 7,584,000 J/kg

Hematite / Fe2O3 (5% of soil mass):

• Specific heat: 650 J/kg*K
• Heating to melting point (1565C): 650 x (1565-20) = 1,004,250 J/kg
• Latent heat of fusion: 209,000 J/kg
• Heating from melting to boiling (3414-1565 = 1849C): 650 x 1849 = 1,201,850 J/kg
• Latent heat of vaporization: 3,770,000 J/kg
• Total hematite: 6,185,100 J/kg

Water (15% of soil mass):

• Specific heat: 4186 J/kg*K
• Heating to boiling (100C): 4186 x (100-20) = 334,880 J/kg
• Latent heat of vaporization: 2,257,000 J/kg
• Total water: 2,591,880 J/kg

Weighted average (energy per kg of soil): (0.40 x 13,925,320) + (0.20 x 8,710,000) + (0.15 x 7,584,000) + (0.05 x 6,185,100) + (0.15 x 2,591,880)= 5,570,128 + 1,742,000 + 1,137,600 + 309,255 + 388,782= 9,147,765 J/kg≈ 9,148 kJ/kg

Energy per cm3: 9,147,765 x 0.0027 = 24,699 J/cm3≈ 24,700 J/cm3

I've seen some people using this calc but it's wrong.

First, the boiling point of 1200C comes from answers.com with the calc author admitting "soil should be somewhat similar I guess", which is not a real source. No mineral found in soil actually boils at 1200C. Quartz boils at 2904C, hematite at 3414C, feldspar at around 3500C. The 1200C figure does not correspond to any real phase transition.

Second, and most importantly, the latent heat of vaporization was completely ignored. Vaporization is not just heating a material to its boiling point. The latent heat of vaporization is the energy required to actually convert the material from liquid to gas, and it is typically the largest portion of the total energy cost. For SiO2, the latent heat of vaporization alone is 11,770 kJ/kg, which is nearly 10 times larger than the heating energy calculated in the original. Skipping this makes the calc fundamentally wrong as a vaporization calculation.

Third, soil was treated as a single homogeneous material. Soil is a mixture of multiple minerals with completely different thermodynamic properties. Using a generic Cp of 800 J/kg*K and a made up boiling point of 1200C does not represent any of the actual components of soil.

The correct approach is to calculate each major soil component separately. Soil is composed of roughly 40% quartz (SiO2), 20% feldspar, 15% kaolinite, 5% hematite, and 15% water by mass. Each component has its own specific heat, melting point, latent heat of fusion, boiling point, and latent heat of vaporization, and all of these must be included for a proper vaporization calculation.

Using the latent heat of vaporization for SiO2 of 11,770 kJ/kg sourced from a peer reviewed planetary impact study, and applying the full heating plus phase transition energy for each soil component, the correct vaporization energy for soil is approximately 24,700 J/cc for average soil moisture, compared to the 2,592 J/cc currently used. That is roughly 9.5 times higher than the standard value. I can blog this calc if we reach a conclusion.

 

[Saqphire]

Je suis d’accord

 

[Da3ggman]

Definitely agree, spent way too long finding my own value when I did a calc with it, would be a lot easier to have an established value.

 

[M3X_2.0]

@Floxy178 @TheRustyOne @Migue79 @AbaddonTheDisappointment @Dalesean027

 

[FinePoint]

Doesn't the composition of soil depend heavily on the location? For example, in Hawaii, a typical soil is only 50% solid. Also, either way doesn't the average actually have a lot more water and gas?

 

[AyOgUyS]

Doesn't the composition of soil depend heavily on the location? For example, in Hawaii, a typical soil is only 50% solid. Also, either way doesn't the average actually have a lot more water and gas?

We could have separate values for each notably different type of soil methinks.

 

[HammerStrikes219]

First, the boiling point of 1200C comes from answers.com with the calc author admitting "soil should be somewhat similar I guess", which is not a real source. No mineral found in soil actually boils at 1200C. Quartz boils at 2904C, hematite at 3414C, feldspar at around 3500C. The 1200C figure does not correspond to any real phase transition.

“It will take about 1200 to 1500deg C+ to melt dirt. All you will get in the end is a blob of mostly amorphous silica.” For the source that person linked to


Unironically, it was the melting point of Dirt, not vaporization of dirt. Edit: Melting is from changing from a solid to a liquid which is obviously not boiling.

The person who did the calculation you linked literally mixed up melting point of dirt with vaporization which is obviously incorrect.

I don’t get why they thought it was vaporization there.


Edit:


Oh, someone did turn the dirt into a lavalike state as a example of melting.

 

[Foriaa]

24,700 J/cc

Practically the same for rock

 

[Da3ggman]

Practically the same for rock

Well, it is made up mostly of rock, so that’s to be expected ig

 

[Foriaa]

Shh

 

[M3X_2.0]

Doesn't the composition of soil depend heavily on the location? For example, in Hawaii, a typical soil is only 50% solid. Also, either way doesn't the average actually have a lot more water and gas?

Soil composition does vary significantly by location, and the calculation I presented uses what is typically referred to as a reference mineral soil, which is the standard model used in soil science literature. The classic volumetric composition of 45% minerals, 25% water, 25% air, and 5% organic matter is the textbook average for temperate agricultural soil and is the most commonly cited reference in soil physics.

Different soil types do exist and have very different compositions. Hawaiian soils are dominated by volcanic minerals like basalite and olivine rather than the quartz and feldspar used here. Tropical soils like Brazilian latosols are rich in iron and aluminum oxides. Sandy soils are almost entirely quartz. Clay soils are dominated by clay minerals. Each of these would produce a different vaporization energy.

The same logic applies to rock. The vaporization energy of rock also varies significantly depending on its composition. Basalt, granite, sandstone, limestone and other rock types all have different mineral compositions and therefore different thermodynamic properties. Despite this, the wiki uses a single standard value of 25,700 J/cc for rock vaporization regardless of type (we don't have any values for vaporization for limestone or sandstone, despite having for pulverization. We do for granite though which is also very close to the other minerals), because establishing a separate value for every rock type found on Earth would be impractical and the standard reference value serves as a reasonable average for calculation purposes. The same reasoning applies to soil. Using the reference mineral soil composition as a standard value is consistent with how rock vaporization is already handled on the wiki.

With that said, for calc purposes the most defensible approach is to use the reference mineral soil as a low end, since it represents the most widely cited average in the scientific literature. If the feat takes place in a specific location with a known soil type, a more precise calculation could be done for that specific composition. The value of 24,700 J/cc should therefore be treated as a reasonable low end for generic soil vaporization rather than a universal figure.

 

[M3X_2.0]

If we're gonna be anal about it, we can also calculate wet, dry and medium wet soil. Dry is 26500, medium is 24700 and wet is 20000. Now imagine doing that for every single type of soil. I don't wanna do that work, I'm not paid enough.

 

[Saqphire]

If we're gonna be anal about it, we can also calculate wet, dry and medium wet soil. Dry is 26500, medium is 24700 and wet is 20000. Now imagine doing that for every single type of soil. I don't wanna do that work, I'm not paid enough.

Just use medium and call it a day gng

 

[FinePoint]

With that said, for calc purposes the most defensible approach is to use the reference mineral soil as a low end, since it represents the most widely cited average in the scientific literature. If the feat takes place in a specific location with a known soil type, a more precise calculation could be done for that specific composition. The value of 24,700 J/cc should therefore be treated as a reasonable low end for generic soil vaporization rather than a universal figure.

I understand we have to make some generalizations, but I'm just worried the very significant differences between types of soils may lead to heavily inflated statistics, and I know that people get extremely comfortable using general values even when more specific ones could easily be found.

I obviously wouldn't suggest getting a standard value for every type of soil, but I would find your suggestion of perhaps three different types an acceptable compromise.

 

[M3X_2.0]

I understand we have to make some generalizations, but I'm just worried the very significant differences between types of soils may lead to heavily inflated statistics.

I obviously wouldn't suggest getting a standard value for every type of soil, but I would find your suggestion of perhaps three different types an acceptable compromise.

If you can suggest which types of soil, and if other CGM agree with those suggestions, I can calc it. But it'll take some time though.

 

[FinePoint]

If you can suggest which types of soil, and if other CGM agree with those suggestions, I can calc it. But it'll take some time though.

Following a discussion on Discord, we agreed that the following types would be good to have standard values for:

I think this would be diverse enough to avoid too much generalization, but simple enough as to not make things too complicated.

This way people who don't know much about it can just sort of pick one of four based on what can be seen in the feat.

Anything even more specific could just be calced separately.

 

[M3X_2.0]

I agree with that, and when more CGMs comment here, I'll start calculating those.

 

[Saqphire]

Following a discussion on Discord, we agreed that the following types would be good to have standard values for:

I think this would be diverse enough to avoid too much generalization, but simple enough as to not make things too complicated.

This way people who don't know much about it can just sort of pick one of four based on what can be seen in the feat.

Anything even more specific could just be calced separately.

Is there a problem combining the four and dividing the total value for an average here?

 

[FinePoint]

Is there a problem combining the four and dividing the total value for an average here?

Yes, the problem is that there's a very significant gap between the low end and the high end.

By averaging them we'd be systematically either overstating or downplaying feats.

I mean we'll still be doing a lot of averaging for calculating these broad categories, but the margins of error won't be as extreme.

(Or if they're calculated and end up being very similar anyway I'll concede it doesn't matter.)

 

[Saqphire]

Yes, the problem is that there's a very significant gap between the low end and the high end.

By averaging them we'd be systematically either overstating or downplaying feats.

I mean we'll still be doing a lot of averaging for calculating these broad categories, but the margins of error won't be as extreme.

(Or if they're calculated and end up being very similar anyway I'll concede it doesn't matter.)

So the highest and lowest type has too great of a disparity. Makes sense

 

[YmTheSuper]

Soil density: 2.7 g/cm3

The density used here is the particle density of soil.

You should rather use the bulk density of soil (1.3 g/cm^3 on average, here's a range for bulk densities based on the type of the soil, we see that soil with bulk density greater than 1.6 g/cm^3 tends to restrict tree root growth) to account for the pores in the soil, since we calculate the vaporization of a volume of dirt in calculations which would include the volume taken by the air. This is needed since the composition of soil you used is the particle composition which doesn't account for porosity (the air between the individual grains/particles).

 

[FinePoint]

I found a great website that lets us take soil samples from anywhere in the UK basically, but it seems tedious as you have to individually look at each element.

Still, it should technically have all the info we'd need for estimates if we can't find something formatted more friendly.

 

[M3X_2.0]

The density used here is the particle density of soil.

You should rather use the bulk density of soil (1.3 g/cm^3 on average, here's a range for bulk densities based on the type of the soil, we see that soil with bulk density greater than 1.6 g/cm^3 tends to restrict tree root growth) to account for the pores in the soil, since we calculate the vaporization of a volume of dirt in calculations which would include the volume taken by the air. This is needed since the composition of soil you used is the particle composition which doesn't account for porosity (the air between the individual grains/particles).

The air in the pores is already a gas and requires no energy to vaporize, so it was excluded from the energy calculation entirely. Using bulk density (1.3 g/cc) automatically accounts for the air fraction by diluting the total mass, but since the air was already explicitly excluded from the composition used in this calc, using particle density (2.7 g/cc) only for the solid fraction is consistent with the same logic. Both approaches arrive at the same place: bulk density applied to the total volume equals particle density applied to the solid volume only. Since this calc already treats each component individually and excludes air, 2.7 g/cc is the correct density for the material actually being vaporized.

 

[YmTheSuper]

The air in the pores is already a gas and requires no energy to vaporize, so it was excluded from the energy calculation entirely. Using bulk density (1.3 g/cc) automatically accounts for the air fraction by diluting the total mass, but since the air was already explicitly excluded from the composition used in this calc, using particle density (2.7 g/cc) only for the solid fraction is consistent with the same logic. Both approaches arrive at the same place: bulk density applied to the total volume equals particle density applied to the solid volume only. Since this calc already treats each component individually and excludes air, 2.7 g/cc is the correct density for the material actually being vaporized.

The problem is that the volumes calculated within calculations include the pores as they aren't individually counting the solid volume on its own but rather the full bulk volume.

The vaporisation value derived here from 2.7 g/cc would work but only if the porosity is accounted for when counting the volume in the calculation via subtracting the volume of the air.

So if that is the value we use we have to make sure that every calc removes the air volume from the total volume before using the vaporisation value when using the bulk density to derive a vaporisation value and then simply multiplying it by the initial volume would be more straightforward, less confusing for members and require less steps.

 

[Flashlight237]

I'll be the anal one over here because the inconsistencies here annoy me. First, you're assuming soil has a density of 2.7 g/cm³, which... NO, that's not the case. Soil is not a solid rock; it's a loose material. Soil has a density of 1.1 to 1.6 g/cm³: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/soil-density

Loam (the stuff you mostly think about when it comes to soil) is in the middle ground in regards to density, so let's assume 1.35 g/cm³ for soil.

So, I have previously taken on this exact topic in a recalc of one of @Mr. Bambu 's Danny Phantom calcs, as you can see here: https://vsbattles.fandom.com/wiki/User_blog:Flashlight237/Danny_Phantom_Recalc:_The_Meat_Crater

With the original source being this kids' education page from the University of Illinois: https://web.extension.illinois.edu/gpe/case2/c2facts1.html

That being said, here's all the info I have for silica: https://vsbattles.fandom.com/wiki/U...lc_Value_Fixes_+_A_New_Material_or_Two#Silica

You could've just asked me for it since it's got all the info and sources you need, but instead, ya went and made up an uncited latent heat of fusion for silica. Please don't make up numbers out of thin air; all that does is gaslight people. Google is your friend.

So let's do what I did from that Danny Phantom recalc, here's what I can gather...

Granite: 790 J/kg K specific heat capacity (see Wikipedia table), 1570 J/kg K specific heat capacity when liquid, 220-250 kJ/kg (235 kJ/kg median) latent heat of fusion, 4800-5300 kJ/kg (5050 kJ/kg) latent heat of vaporization; density of 2700 kg/m³, melts at 1215-1260°C (median of 1237.5°C)
Water: 4190 J/kg K mean specific heat capacity while liquid (i.e. the Mean Calorie), 2030 J/kg K specific heat capacity as steam, 2257000 J/kg heat of vaporization, density of 1000 kg/m³
Air: 1007 J/kg K specific heat capacity at 20°C, density of 1.184 kg/m³

Change in Temperature: 2940°C (assuming lowest vaporization temperature of granite is 2960°C and the base temperature is 20°C)

Assuming 1 cubic meter of soil, we have 0.45 cubic meters of granite, 0.25 cubic meters of water, and 0.25 cubic meters of air. Let's see...

Granite (1215 kg): (790*1217.5*1215)+(1570*1722.5*1215)+(235000*1215)+(5050000*1215)=10875647250 joules
Water (250 kg): (4190*80*250)+(2030*2840*250)+(2257000*250)=2089350000 joules
Air (0.296 kg): 1007*2940*0.296=876331.68 joules
Total Accountable For: 10875647250+2089350000+876331.68=12965873581.7 joules per cubic meter

Divide all this by 100³ and you get 12965.8735817 J/cm³ for soil vaporization. That's nowhere near 24700 J/cm³.

 

[M3X_2.0]

I'll be the anal one over here because the inconsistencies here annoy me. First, you're assuming soil has a density of 2.7 g/cm³, which... NO, that's not the case. Soil is not a solid rock; it's a loose material. Soil has a density of 1.1 to 1.6 g/cm³: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/soil-density

Loam (the stuff you mostly think about when it comes to soil) is in the middle ground in regards to density, so let's assume 1.35 g/cm³ for soil.

So, I have previously taken on this exact topic in a recalc of one of @Mr. Bambu 's Danny Phantom calcs, as you can see here: https://vsbattles.fandom.com/wiki/User_blog:Flashlight237/Danny_Phantom_Recalc:_The_Meat_Crater

With the original source being this kids' education page from the University of Illinois: https://web.extension.illinois.edu/gpe/case2/c2facts1.html

That being said, here's all the info I have for silica: https://vsbattles.fandom.com/wiki/User_blog:Flashlight237/Some_Calc_Value_Fixes_+_A_New_Material_or_Two#Silica

You could've just asked me for it since it's got all the info and sources you need, but instead, ya went and made up an uncited latent heat of fusion for silica. Please don't make up numbers out of thin air; all that does is gaslight people. Google is your friend.

So let's do what I did from that Danny Phantom recalc, here's what I can gather...

Granite: 790 J/kg K specific heat capacity (see Wikipedia table), 1570 J/kg K specific heat capacity when liquid, 220-250 kJ/kg (235 kJ/kg median) latent heat of fusion, 4800-5300 kJ/kg (5050 kJ/kg) latent heat of vaporization; density of 2700 kg/m³, melts at 1215-1260°C (median of 1237.5°C)
Water: 4190 J/kg K mean specific heat capacity while liquid (i.e. the Mean Calorie), 2030 J/kg K specific heat capacity as steam, 2257000 J/kg heat of vaporization, density of 1000 kg/m³
Air: 1007 J/kg K specific heat capacity at 20°C, density of 1.184 kg/m³

Change in Temperature: 2940°C (assuming lowest vaporization temperature of granite is 2960°C and the base temperature is 20°C)

Assuming 1 cubic meter of soil, we have 0.45 cubic meters of granite, 0.25 cubic meters of water, and 0.25 cubic meters of air. Let's see...

Granite (1215 kg): (790*1217.5*1215)+(1570*1722.5*1215)+(235000*1215)+(5050000*1215)=10875647250 joules
Water (250 kg): (4190*80*250)+(2030*2840*250)+(2257000*250)=2089350000 joules
Air (0.296 kg): 1007*2940*0.296=876331.68 joules
Total Accountable For: 10875647250+2089350000+876331.68=12965873581.7 joules per cubic meter

Divide all this by 100³ and you get 12965.8735817 J/cm³ for soil vaporization. That's nowhere near 24700 J/cm³.

First, the density point is fair and was already conceded earlier in the thread. We acknowledged that bulk density should be used instead of particle density, and 1.3 g/cm³ was agreed upon, which is consistent with your 1.35 figure.

Second, regarding the latent heat of fusion for silica being “made up”, that is incorrect. The value of 50 kJ/kg for SiO2 latent heat of fusion comes from standard thermodynamic tables and is consistent with published literature. It is a small value and barely affects the final result either way, so calling it gaslighting is a significant overreaction.

Third, and most importantly, your calculation uses granite as a proxy for soil minerals, which is a reasonable simplification, but it actually supports the general approach used here rather than contradicting it. The main methodological difference is that your calc uses 5050 kJ/kg as the latent heat of vaporization for granite, while our calc used 11770 kJ/kg for pure SiO2 sourced from a peer reviewed planetary impact study. That difference is the primary reason the values diverge, not the density or the fusion values.

The SiO2 vaporization value of 11770 kJ/kg comes from here: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012JE004082

Granite is not pure SiO2. It contains feldspar, mica, and other minerals that lower the bulk vaporization energy relative to pure quartz. If you are using granite as the soil mineral proxy, that is a legitimate simplification, but it does not make our approach wrong. It makes it a higher end, which is defensible depending on what the soil in the feat actually consists of.

So the actual disagreement is not about made up numbers or gaslighting. It is about which mineral proxy best represents soil and which latent heat of vaporization source is more appropriate. Both are valid discussion points. And cut the condescending tone. You are not in any position to talk to people like that, and you never have been. This is not the first time you have come across as weirdly superior when addressing others on this wiki, and it is not a good look. You will drop that attitude now.

Also, “you could’ve just asked me” is funny. No offense but I am not required to consult you before running a calculation, and your wiki blog is not the official standard for thermodynamic values. The latent heat of fusion for SiO2 is freely available in actual scientific literature and does not require asking anyone on a fiction debate forum. Google is indeed a friend, which is why the vaporization value was sourced from a peer reviewed AGU journal paper rather than a kids education page from the University of Illinois.

 

[Dalesean027]

You could've just asked me for it since it's got all the info and sources you need, but instead, ya went and made up an uncited latent heat of fusion for silica. Please don't make up numbers out of thin air; all that does is gaslight people. Google is your friend.

This bit is highly unnecessary, dude did research and thought he found valid sources, you can't entirely fault him for that and that certainly doesn't give you fair grounds to call him liar whose trying to gaslight people. Refrain from that kinda shit moving forward as its highly disrespectful to those here

 

[M3X_2.0]

Funny how four proper calculations with full thermodynamic methodology, peer reviewed sources, and latent heat included can be done without crawling to the self-appointed soil expert of the VS Battles Wiki to ask for his blessing. Here are the results:

Spoiler: Silt soil

Silt Soil Vaporization Calculation

Silt soil composition by mass: 55% SiO2 (quartz), 20% feldspar, 10% kaolinite, 10% water, 5% hematite. Air fraction excluded. Bulk density: 1.2 g/cc (0.0012 kg/cc). Starting temperature: 20C.

Source for silt soil composition:
USDA Soil Texture Guide

Source for SiO2 latent heat of vaporization (11,770 kJ/kg) and boiling point (3177K / 2904C):
AGU Quartz Thermodynamics Study

Source for specific heat and density:
Engineering Toolbox – Specific Heat Capacity

SiO2 (55% of soil mass):
Specific heat: 730 J/kg*K
Heating to melting point (1710C):
730 x (1710-20) = 1,233,700 J/kg
Latent heat of fusion: 50,000 J/kg
Heating from melting to boiling (2904-1710 = 1194C):
730 x 1194 = 871,620 J/kg
Latent heat of vaporization: 11,770,000 J/kg
Total SiO2:
13,925,320 J/kg

Feldspar (20% of soil mass):
Specific heat: 750 J/kg*K
Heating to melting point (1220C):
750 x (1220-20) = 900,000 J/kg
Latent heat of fusion: 100,000 J/kg
Heating from melting to boiling (~3500C):
750 x (3500-1220) = 1,710,000 J/kg
Latent heat of vaporization: 6,000,000 J/kg
Total feldspar:
8,710,000 J/kg

Kaolinite (10% of soil mass):
Specific heat: 900 J/kg*K
Heating to decomposition/melting point (1775C):
900 x (1775-20) = 1,579,500 J/kg
Latent heat of fusion/decomposition: 200,000 J/kg
Heating from melting to boiling (~2500C):
900 x (2500-1775) = 652,500 J/kg
Latent heat of vaporization: 3,500,000 J/kg
Total kaolinite:
5,932,000 J/kg


Source for kaolinite thermodynamic properties:
Kaolinite Mineral Data

Water (10% of soil mass):
Specific heat: 4186 J/kg*K
Heating to boiling (100C):
4186 x (100-20) = 334,880 J/kg
Latent heat of vaporization: 2,257,000 J/kg
Total water:
2,591,880 J/kg

Source for water thermodynamic properties:
Engineering Toolbox – Water Properties

Hematite (5% of soil mass):
Specific heat: 650 J/kg*K
Heating to melting point (1565C):
650 x (1565-20) = 1,004,250 J/kg
Latent heat of fusion: 250,000 J/kg
Heating from melting to boiling (~3400C):
650 x (3400-1565) = 1,192,750 J/kg
Latent heat of vaporization: 3,500,000 J/kg
Total hematite:
5,947,000 J/kg

Source for hematite mineral properties:
Hematite Mineral Data

Weighted average energy per kg of silt soil:
(0.55 x 13,925,320) + (0.20 x 8,710,000) + (0.10 x 5,932,000) + (0.10 x 2,591,880) + (0.05 x 5,947,000)

= 7,658,926 + 1,742,000 + 593,200 + 259,188 + 297,350 = 10,550,664 J/kg

Energy per cc:
10,550,664 x 0.0012 = 12,661 J/cc

Spoiler: Loam soil

Loam Soil Vaporization Calculation

Loam soil composition by mass: 40% SiO2 (quartz), 20% feldspar, 15% kaolinite, 15% water, 5% hematite. Air fraction excluded. Bulk density: 1.3 g/cc (0.0013 kg/cc). Starting temperature: 20C.

• Source for SiO2 latent heat of vaporization (11,770 kJ/kg) and boiling point (2904C): https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012JE004082
• Source for specific heat and density: https://www.engineeringtoolbox.com/specific-heat-capacity-d_391.html

SiO2 (40% of soil mass): Specific heat: 730 J/kg*K. Heating to melting point (1710C): 730 x (1710-20) = 1,233,700 J/kg. Latent heat of fusion: 50,000 J/kg. Heating from melting to boiling (1194C difference): 730 x 1194 = 871,620 J/kg. Latent heat of vaporization: 11,770,000 J/kg. Total SiO2: 13,925,320 J/kg.

Feldspar (20% of soil mass): Specific heat: 750 J/kg*K. Heating to melting point (1220C): 750 x (1220-20) = 900,000 J/kg. Latent heat of fusion: 100,000 J/kg. Heating from melting to boiling (3500C): 750 x (3500-1220) = 1,710,000 J/kg. Latent heat of vaporization: 6,000,000 J/kg. Total feldspar: 8,710,000 J/kg.

Kaolinite (15% of soil mass): Specific heat: 800 J/kg*K. Heating to decomposition point (1775C): 800 x (1775-20) = 1,404,000 J/kg. Latent heat of fusion/decomposition: 200,000 J/kg. Heating from melting to boiling (2500C): 800 x (2500-1775) = 580,000 J/kg. Latent heat of vaporization: 3,500,000 J/kg. Total kaolinite: 5,684,000 J/kg.

Hematite (5% of soil mass): Specific heat: 650 J/kg*K. Heating to melting point (1565C): 650 x (1565-20) = 1,004,250 J/kg. Latent heat of fusion: 209,000 J/kg. Heating from melting to boiling (3414C): 650 x (3414-1565) = 1,201,850 J/kg. Latent heat of vaporization: 3,770,000 J/kg. Total hematite: 6,185,100 J/kg.

Water (15% of soil mass): Specific heat: 4186 J/kg*K. Heating to boiling (100C): 4186 x (100-20) = 334,880 J/kg. Latent heat of vaporization: 2,257,000 J/kg. Total water: 2,591,880 J/kg.

Weighted average energy per kg of loam: (0.40 x 13,925,320) + (0.20 x 8,710,000) + (0.15 x 5,684,000) + (0.05 x 6,185,100) + (0.15 x 2,591,880) = 5,570,128 + 1,742,000 + 852,600 + 309,255 + 388,782 = 8,862,765 J/kg

Energy per cc: 8,862,765 x 0.0013 = 11,521 J/cc

Spoiler: Clay soil

Clay Soil Vaporization Calculation

Clay soil composition by mass: 20% SiO2 (quartz), 10% feldspar, 30% kaolinite, 20% montmorillonite/illite, 20% water. Air fraction excluded. Bulk density: 1.1 g/cc (0.0011 kg/cc). Starting temperature: 20C.

Source for clay soil composition:
USDA Soil Texture Guide

Source for SiO2 latent heat of vaporization (11,770 kJ/kg) and boiling point (3177K / 2904C):
AGU Quartz Thermodynamics Study

Source for specific heat and density:
Engineering Toolbox – Specific Heat Capacity

SiO2 (20% of soil mass):
Specific heat: 730 J/kg*K
Heating to melting point (1710C):
730 x (1710-20) = 1,233,700 J/kg
Latent heat of fusion: 50,000 J/kg
Heating from melting to boiling (2904-1710 = 1194C):
730 x 1194 = 871,620 J/kg
Latent heat of vaporization: 11,770,000 J/kg
Total SiO2:
13,925,320 J/kg

Feldspar (10% of soil mass):
Specific heat: 750 J/kg*K
Heating to melting point (1220C):
750 x (1220-20) = 900,000 J/kg
Latent heat of fusion: 100,000 J/kg
Heating from melting to boiling (~3500C):
750 x (3500-1220) = 1,710,000 J/kg
Latent heat of vaporization: 6,000,000 J/kg
Total feldspar:
8,710,000 J/kg

Kaolinite (30% of soil mass):
Specific heat: 900 J/kg*K
Heating to decomposition/melting point (1775C):
900 x (1775-20) = 1,579,500 J/kg
Latent heat of fusion/decomposition: 200,000 J/kg
Heating from melting to boiling (~2500C):
900 x (2500-1775) = 652,500 J/kg
Latent heat of vaporization: 3,500,000 J/kg
Total kaolinite:
5,932,000 J/kg

Source for kaolinite thermodynamic properties:
Kaolinite Mineral Data

Montmorillonite/Illite (20% of soil mass):
Specific heat: 1000 J/kg*K
Heating to decomposition point (1300C):
1000 x (1300-20) = 1,280,000 J/kg
Latent heat of fusion/decomposition: 200,000 J/kg
Heating from melting to boiling (~2500C):
1000 x (2500-1300) = 1,200,000 J/kg
Latent heat of vaporization: 3,000,000 J/kg
Total montmorillonite/illite:
5,680,000 J/kg

Source for clay mineral thermodynamics:
Clay Mineral Thermodynamics Study

Water (20% of soil mass):
Specific heat: 4186 J/kg*K
Heating to boiling (100C):
4186 x (100-20) = 334,880 J/kg
Latent heat of vaporization: 2,257,000 J/kg
Total water:
2,591,880 J/kg

Source for water thermodynamic properties:
Engineering Toolbox – Water Properties

Weighted average energy per kg of clay soil:
(0.20 x 13,925,320) + (0.10 x 8,710,000) + (0.30 x 5,932,000) + (0.20 x 5,680,000) + (0.20 x 2,591,880)

= 2,785,064 + 871,000 + 1,779,600 + 1,136,000 + 518,376 = 7,090,040 J/kg

Energy per cc:
7,090,040 x 0.0011 = 7,799 J/cc

Spoiler: Sandy soil

Sandy Soil Vaporization Calculation

Sandy soil composition by mass: 85% SiO2 (quartz), 10% feldspar, 5% water. Air fraction excluded. Bulk density: 1.3 g/cc (0.0013 kg/cc). Starting temperature: 20C.

• Source for sandy soil composition: https://chicagolandgardening.com/gardening-basics/understanding-soil/what-is-sandy-soil/
• Source for SiO2 latent heat of vaporization (11,770 kJ/kg) and boiling point (2904C): https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012JE004082
• Source for specific heat and density: https://www.engineeringtoolbox.com/specific-heat-capacity-d_391.html

SiO2 (85% of soil mass): Specific heat: 730 J/kg*K. Heating to melting point (1710C): 730 x (1710-20) = 1,233,700 J/kg. Latent heat of fusion: 50,000 J/kg. Heating from melting to boiling (1194C difference): 730 x 1194 = 871,620 J/kg. Latent heat of vaporization: 11,770,000 J/kg. Total SiO2: 13,925,320 J/kg.

Feldspar (10% of soil mass): Specific heat: 750 J/kg*K. Heating to melting point (1220C): 750 x (1220-20) = 900,000 J/kg. Latent heat of fusion: 100,000 J/kg. Heating from melting to boiling (3500C): 750 x (3500-1220) = 1,710,000 J/kg. Latent heat of vaporization: 6,000,000 J/kg. Total feldspar: 8,710,000 J/kg.

Water (5% of soil mass): Specific heat: 4186 J/kg*K. Heating to boiling (100C): 4186 x (100-20) = 334,880 J/kg. Latent heat of vaporization: 2,257,000 J/kg. Total water: 2,591,880 J/kg.

Weighted average energy per kg of sandy soil: (0.85 x 13,925,320) + (0.10 x 8,710,000) + (0.05 x 2,591,880) = 11,836,522 + 871,000 + 129,594 = 12,837,116 J/kg

Energy per cc: 12,837,116 x 0.0013 = 16,688 J/cc

All four calculations use bulk density to account for porosity, full heating curves for each mineral component, latent heat of fusion, and latent heat of vaporization. The lowest value is clay soil at ~7,799 J/cc and the highest is sandy soil at ~16,680 J/cc due to its dominant quartz content and the correspondingly high SiO2 latent heat of vaporization of 11,770 kJ/kg sourced from a peer reviewed AGU planetary impact study.

 

[FinePoint]

The lowest value is clay soil at ~7,799 J/cc and the highest is sandy soil at ~16,680 J/cc

As I expected, that is a very big difference!

The silt and loam are very similar though, so I'd be okay lumping those together into an average if we wanted.

Otherwise, I'm happy to have these four values, and they should cover most bases (assuming the math checks out, which is above my paygrade).

 

[Nierre]

the world shall know bump