Gas/Liquid pressure from temperature and density
How can I calculate a gas' or a liquid's pressure from it's density and it's temperature? For example, for air, I suppose the pressure and the density is proportional, . Is this true? That would mean that since the unit of pressure is and the unit for density is , the unit for pressure per density would be , or , or . Im just thinking a little bit. And since the atmospherical pressure is , and the air density in one atm pressure is to heaped in normal temperatures (here in Sweden). So then we can say that
Now I don't know if this is true. And this is only for the temperature .
Then I guess It is not the same thing at all with liquids, not water at least. Since the density for water (in ) is always but the pressure can change. Okay I guess that is not completely true, but almost.