Nature and chemistry of water

What is “water“?

The word “water“
The word originates from the Germanic word “wæter”

Chemically
From the chemical point of view, water (H2O) is a compound consisting of the elements oxygen (O) and hydrogen (H). The atoms are not aligned in a straight row. Between both H-atoms and the O-atom lies an angle of approximately 108 degrees.

Because of this angle, the molecule is not neutral to the outside. It is negatively charged around the O-atom and positively charged around the H-atoms (dipole). This is why water molecules attract one another. The asymmetrical alignment of the positive and negative charges in the water molecule is known as „hydrogen bond“.

The water’s surface tension enables small animals, for example water skaters, to skeet over the water without sinking. Yet the surface tension can be damaged, for example by adding washing up liquid.

Skeet across the water’s surface: water skaters

Why does water “flow” from the tap like a “rope of water”?

Flowing water is nothing but a row of drops of water. They move in this alignment as if they were beads on a string. One drop follows the other, they stick together because of cohesive power.

The drain in a bathtub or sink is circular. If a water drop flowing towards it has enough impetus, it will follow this shape: it flows in a circle. Following drops go the same way. That is why draining larger quantities of water leads to swirls in the bathtub.

Thanks to the firm connection between water molecules, plants can suck water up from their roots to their leaves.

Solid, liquid, gaseous – the physical conditions of water

H2O (water) is the only chemical compound in the world that appears in all three physical conditions naturally: ice (frozen solid), steam (gaseous) and liquid.

Water freezes at 0 °C on earth and boils at 100 °C.

At approximately 4 °C, water reaches its maximum density. If it is cooled even more, it freezes to ice and begins expanding again. This is the reason why icebergs float and deep lakes do not freeze at the bottom. Thanks to this, animals that live in the water can survive winter. Sealed glass bottles that are filled to the brim with water can explode when frozen. This is also

The three physical conditions of water in one picture

Water as a solvent

Water is a good solvent for different substances. When a substance is dissolved, the ions that were partially positively and partially negatively charged are broken down. They then swim in the water and can join to form other compounds.

Oil and wax, on the other hand, are not soluble in water. Oil swims on and in water in drops. Even when stirred vigorously, the oil droplets gather on the water’s surface. If you add washing up liquid, the particles no longer mix and an emulsion forms. For example creams and body lotions.

Positively or negatively charged ions (=particles) like salts or other polar liquids dissolve very well in water.

Most solid, liquid and gaseous substances can be absorbed by water. This is especially important for nutrient balance in living creatures and for the oxygen supply process.

If salt is dissolved in water, the resulting solution only freezes under 0°C. That is why salt can be used to thaw ice in the winter. The freezing point can be lowered to minus 21°C.

Water evaporation

The atmosphere mainly absorbs water on the earth’s surface (water surfaces, puddles, soil and plants). As long as the air is not saturated with steam, water already evaporates at room temperature. The fact that washing dries in the open air and puddles disappear is based on this phenomenon.

Water is released onto the skin when we sweat and then evaporates. Energy in form of heat is withdrawn from the body. The skin’s surface is cooled.

Leaves that cannot avoid solar radiation evaporate through an opening on the bottom side of the leaves and thus lower the temperature.

Mammals like dogs, for example, cool themselves through panting. The Asian elephant can remove saliva from inside its cheeks and spread it over its body. The African elephant cannot do so, but has large ears instead. He releases excess heat over his well circulated ears, through which up to 14 litres of blood flow per minute.

Heat storage

Water can absorb an exceptionally large amount of warmth whilst warming up slowly. It has a high thermal capacity.

This is why large amounts of water have such a great impact on the climate.

The climate is oceanic near large amounts of water, i.e. the winters are mild and summers are relatively cool. On the inside of continents, summers are likely to be hotter and winters colder.

Water as a heat conductor

Water can also absorb water quickly and easily because water molecules are especially dense. As water does not conduct warmth well, the human body cools down quickly. Yet water only releases warmth relatively slowly. When staying in water under 18°C for a longer period of time, a wetsuit is recommended.

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