Why is it that water is a liquid at room temperature, yet both hydrogen and oxygen are a gas?

Question

Hydrogen becomes a liquid at just below absolute zero. Oxygen is a liquid at almost -300 F. So how is it that water (H2O) is a liquid at room temperature?

Answer 1

Ah, the magic of chemistry. See, combining chemicals and having them react (that is, in this case, covalently bond and share electrons) is so completely different from simply mixing two substances together physically. When you have a chemical reaction, the products can have completely different physical properties from the reactants because they can have completely different chemical properties. Oxygen and hydrogen are two nonpolar molecules, which means that they have relatively weak intermolecular forces and don't attract each other a lot. That causes them to be gaseous, even at low temperatures. They just don't like to stick together that much; they like to be spread out, which results in a gaseous phase. Water molecules, however, are not only polar, but they exhibit hydrogen bonding, one of the strongest intermolecular forces, so they really like to stick to each other, and they like to be close together, which results in a liquid phase at room temperature.

A traditional example of this is sodium and chlorine. Sodium, Na, is a soft metal. Chlorine, Cl, which exists as a diatomic molecule, Cl2, is a yellowish toxic gas (mustard gas). When they react, they form NaCl, which is sodium chloride, table salt. That is drastically different. A metal and a gas formed an ionic salt, which generally have properties very unlike both gases and metals. Go figure.

Answer 2

Water is a molecule that has H attached to O. Because O pulls electrons towards it very hard, the H has a partial positive (+) charge and the O has a partial negative (-) charge. The attraction between these two can lead to an attraction between two molecules that is of the order of 1% as strong as a full chemical bond - It is called a hydrogen bond. The stronger-than-normal attraction between water molecules tends to hold them back from volatilising into the gas phase, so it remains as a liquid. Alternatively, the attraction between molecules is sufficiently strong that when they are In the gas phase, they combine to make a liquid. Evidence of the tendency of hydrogen bonding to favor liquids is evident in ethanol (C2H6O) and dimethyl ether (C2H6O). Although they have the same mass (making them equally difficult or easy to move into the gas phase, ethanol has a much higher boiling point (of approx 78 degrees C) relative to dimethyl ether (approx 30 C[?]). This is because the O is attached to a H in ethanol and is only attached to 2 C's in dimethyl ether. So ethanol can hydrogen bond and dimethyl ether cannot (because O cannot create a partial positive charge in C like it does with H). Hope this is not too technical....

Answer 3

Because when then come together they create covalent bonds that attract other water molecules that when at room temperature are close enough to each other to create a liquid. When heated their speed increases and the seperate changing to a gas. Not all water is liquid at room temp.

Answer 4

because water is a polar molecule.

Answer 5

it is natural law