Oxides of non metal - class-IX

Another form of solid carbon dioxide observed at high pressure is an amorphous glass-like solid. This form of glass, called carbonia, is produced by supercooling heated $C{O} _{2}$ at extreme pressure ($40 48  GPa$ or about $400,000$ atmospheres) in a diamond anvil.
This discovery confirmed the theory that carbon dioxide could exist in a glass state similar to other members of its elemental family, like silicon (silica glass) and germanium dioxide.

Carbon dioxide gas is fairly soluble in water.
Aerated water is a solution of $CO _2$ in water under pressure.

Carbon dioxide is a colourless, odourless and linear molecule. Its structure can be represented as $O=C=O$ The $O-C-O$ bond angle is 180 $^o$. The carbon atom is $sp$ hybridised.

Supercritical carbon dioxide is a fluid state of carbon dioxide where it is held at or above its critical temperature and critical pressure. Carbon dioxide usually behaves as a gas in air at standard temperature and pressure (STP), or as a solid called dry ice when frozen. If the temperature and pressure are both increased from STP to be at or above the critical point for carbon dioxide, it can adopt properties midway between a gas and a liquid.

 Gaseous or liquid carbon dioxide, stored under pressure, will form dry ice through an auto-refrigeration process if rapidly de-pressured.

$2NO+O _2\longrightarrow 2NO _2$

When $NO$ mixes with oxygen, reddish brown fumes of $NO _2$ appears.$2 NO _{(g)} + O _{2(g)}\rightarrow 2NO _{2(g)}$

$H _2S$ burns completely in the presence of oxygen as:

Carbon dioxide is colorless. At low concentrations, the gas is odorless. At higher concentrations it has a sharp, acidic odor. At standard temperature and pressure, the density of carbon dioxide is around $1.98  {kg}/{{m}^{3}}$, about $1.67$ times that of air.

Carbon dioxide gas does not allows the earth to radiate out heat rapidly. So, it is one of the green house gas.

Carbon dioxide exists in Earth's atmosphere as a trace gas at a concentration of about $0.04$ percent $\left(400   ppm\right)$ by volume. A trace gas is a gas which makes up less than $1$% by volume of the Earth's atmosphere.

Burning of carbon is an exothermic reaction because heat is evolved in this reaction.
$C + O _2 \rightarrow CO _2 + $ heat
The enthalpy change is negative.