1
$\begingroup$

The planet in question is this one. The atmosphere mainly consists of nitrogen and is approximately a quarter the density of Earth's; I chose surface temperatures ranging from -50°C to 0°C.

I need a compount which effectively "replaces" water on this planet. Any compounds similar to Water in their composition and their chemical reactions, with oxygen replaced by nitrogen, are welcome; I looked up Azanide (H2N) but could not find information about its chemical and physical properties.

A modification of the surface temperature is allowed, which means that compounds with evaporation temperatures between -100°C and -50°C are permitted too. The difference between the melting and evaporation temperature must be as big as possible.

$\endgroup$
  • $\begingroup$ I doubt if azanide would be a replacement for H2) (water) as this web page suggests it is a molecular subunit of proteins and other complex molecules: wikigenes.org/e/chem/e/2826723.html $\endgroup$ – a4android Mar 3 '17 at 12:35
  • 2
    $\begingroup$ FWIW, earth's atomosphere is 78% gaseous nitrogen already. I'd call that "mainly nitrogen". You're going to need to come up with a good reason why the (relatively stable) diatomic nitrogen would be found in other forms. $\endgroup$ – papidave Mar 4 '17 at 15:56
7
$\begingroup$

Replacing Oxygen with Nitrogen pretty much gets away all the reasons for the peculiar properties of water: highly polar molecule with strong H bonds between molecules, resulting in its relatively high boiling point.

The closest small molecule is ammonia, NH3, which melts at -78 °C and boils at -33 °C. In your indicated temperature range you could have seas of ammonia and gas, but no solid ammonia.

But your planet is less dense, therefore it will have a lower gravity if the size is similar to Earth. A lower gravity means a lower pressure, and therefore you can wave goodbye to your liquid ammonia.

$\endgroup$
  • $\begingroup$ Looked up a phase diagram. cpp.edu/~skboddeker/122/exam/122-07-4fall-e2_files/image005.jpg $\endgroup$ – MedwedianPresident Mar 4 '17 at 14:14
  • $\begingroup$ The highly polar nature of water isn't simply useful because of its influence on melting and boiling points; It also makes water useful as a solvent for a variety of ionic and polar molecules. It also causes ice to be (unlike most materials) less dense as a solid than as a liquid. Ice floats, which allows us to have seas with ice on top that stay mostly liquid. $\endgroup$ – papidave Mar 4 '17 at 15:51

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.