Gas densities

[tracc]

Great game a lot of fun .. etc. etc.

I dont understand why natural gas is heavier than oxygen. in theory the gas density should proportional to the molecular weight. assuming ideal gas behavior and as following:

Hydrogen (H2) MW= 2 g/mol;

Natural Gas (mostly CH4) MW = 16 g/mol;

Oxygen (O2) MW = 32 g/mol;

Polluted Oxygen (O2+X) MW = 32+-x (depends on the pollution, but doesnt matter)

Carbon dioxyd (CO2) MW = 44 g/mol;

Chlorine (Cl2) MW = 70 g/mol;

Did I forget anything?

Why is Natural Gas heavier than Oxygen?

Greetings tracc

[tracc]

Aah I wonted to post in Oxygen not included of course...

Can someone move it, I dont know how

[MrKoopa]

@ImDaMisterL Can you be so kind and use your Mod magic and move this?

[rezecib]

@tracc According to the files, they actually have some incorrect molar masses. I'm not sure if that's what's being used to determine the stratification of gases, but many of the diatomic gases have a molar mass for monoatomic versions. For example, these are the values in the game:

• Chlorine: 34.453 (should be 70ish)
• Oxygen: 15.9994 (should be 32ish as you observed)
• Natural Gas (methane): 16.044 (this is correct, but now you see why the game might think it's heavier)

I didn't go through and check all of them, but those ones I noticed.

(the file I checked was bundle sharedassets0.assets, the file Gas.txt, using Unity Assets Bundle Extractor)

Edit: I should do a bug report... ..done!

[OxyClean]

Looks like they are using the empirical formula for the masses

[brummbar7]

On 6/9/2017 at 4:04 AM, tracc said:

Why is Natural Gas heavier than Oxygen?

Your short answer is probably 'They're not chemists'.   Possibly also 'game balance'.  My bet is on the former. 

[Nidhoggur]

Well, I see 2 possibilities here.
Either, natural gas is not CH4 and is something completely different on those asteroids. C3H8?   Or it's made so by game design.

Or both

[Kasuha]

Natural gas is not just methane, it is a mix of hydrocarbon and other gases, some of them lighter and some heavier than air. In my opinion that name goes better with the fact that it is heavier than oxygen than if it was called Methane but kept that property.

 

[rezecib]

In ONI, Natural Gas is intended to be methane. The files refer to it as methane, and all of its physical properties match methane.

According to this, the molar mass of natural gas is not very different from methane anyway, and oxygen should still have a much higher molar mass.

[Nidhoggur]

Hm... okay then. It appears it is made purely for game balance.
Probably since there are both hydogen and natural gas generators it makes sense to separate those two gasses by weight. So that hydrogen ends up in the top of your base while the natural gas does not.

[Kasuha]

1 hour ago, rezecib said:

In ONI, Natural Gas is intended to be methane. The files refer to it as methane, and all of its physical properties match methane.

According to this, the molar mass of natural gas is not very different from methane anyway, and oxygen should still have a much higher molar mass.

Yes, it was intended to be methane. It was even called methane after it was introduced in closed testing. But then devs chose the orange color for it, and it was heavier than air. And after some discussion they chose to rename it to natural gas over making it lighter than air.

 

[Risu]

1 hour ago, Kasuha said:

Yes, it was intended to be methane. It was even called methane after it was introduced in closed testing. But then devs chose the orange color for it, and it was heavier than air. And after some discussion they chose to rename it to natural gas over making it lighter than air.

 

I assume they choose to rename it as a means to get rid of requiring oxygen for the generator.
Now we can assume the natural gas has oxygen mixed in it.
 

[tracc]

9 hours ago, Kasuha said:

Natural gas is not just methane, it is a mix of hydrocarbon and other gases, some of them lighter and some heavier than air. In my opinion that name goes better with the fact that it is heavier than oxygen than if it was called Methane but kept that property.

 

@Katusha Yeah Natural Gas is about 90 % Methane and some higher Hydrocarbons, N2 and Carbon Dioxide.

I can see why it would not be perfect Gameplay-wise to have all combustible gasses collect at the top. but there should be a way to know what will happen to different gasses before you bring them into your base.

I was also confused, when no generator (especially the Hydrogen Generator) had a liquid output, or produces Steam. But I guess this is also a Gameplay decision.

I expected this:

Coal Generator: Coal (C) + O2 -->CO2 (but it is C-->CO2)

Natural Gas Generator: NG (CH4) +2O2-->CO2 + 2 H2O (but it is NG-->CO2)

Hydrogen Generator:  H2 + 1/2 O2 --> H2O (but it is H2 --> Energy)

Gameplay wise it would probably be too easy if you had so many water producing units (or dirty water).

 

What I dont like right now is that your base loses mass which ist not explained at all and the mass balance of many utilities is also not satisfied (some machines produce and some reduce mass). Like duplicants, they inhale 100g/s Oxygen and exhale 2g/s CO2. What happens to the 98 g/s?

[clamjam]

Well, it IS a game.  I'm sure a good portion of the inaccuracy regarding physics and mass conservation is related to game balance.

[brummbar7]

7 hours ago, tracc said:

What I dont like right now is that your base loses mass

I think they've tried to balance this with endless sources of water and natural gas.  I don't think the problem is running out of things, but having too much of things (except sand perhaps)