The chemical properties of water

Water is essential for all kinds of life, that we know of. The cells of living organisms are full of water, with many other substances dissolved in it. This property: being able to dissolve substances is very important in biology. Water is a good solvent. It's especially good at dissolving ionic compounds - these are compounds that consist of positive and negative particles.

The water molecule is neither positive nor negative - it's neutral - but it does have a positive and a negative side. This allows the charged particles - which are called ions - to dissolve easily. We say that the water molecule is polar. Another effect of the water molecule being polar, is that the positive and the negative sides of different water molecules attract each other. The molecules stay close together, which is why water is a liquid at room temperature.

Other substances with molecules about the same size as water molecules - are all gases at room temperature. Water however, doesn't boil until the temperature reaches a hundred degrees Celsius. The water molecule consists of oxygen and hydrogen. This means that water can be produced by burning hydrogen gas. Hydrogen gas reacts with the oxygen in the air to form water.

The hydrogen doesn't have to come from hydrogen gas: Almost everything that will burn - paper, wood, petrolium, natural gas - contains hydrogen. All of these release water vapor when burned. You might think of water as a stable compound. It doesn't react with stone, or plastic, or your skin. However, some metals react with water, making the water release hydrogen gas.

One element that reacts violently with water is potassium. The reaction usually releases so much heat that the hydrogen gas ignites. Calcium also reacts with water, giving off hydrogen gas, but the reaction is much slower. Magnesium shows almost no reaction at all with cold water, but with hot water, the reaction is a little faster. Some metals, such as zinc and iron, don't react with liquid water, but zinc powder and iron filings will react with hot steam.

These are some of the chemical properties of water: It is a good solvent for many substances. It has a high boiling point compared to other substances with molecules of similar size. Water is produced when hydrogen-containing substances burn in air. Some metals react with water, producing hydrogen gas. The reaction is violent with some metals such as potassium... ...

slower with other metals such as calcium and magnesium... ... and only possible using hot steam in the case of zinc and iron.