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Science

Useful products from air and seawater

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The atmosphere is a useful raw material. Nitrogen and oxygen can be separated from liquid air by fractional distillation. Seawater is a useful raw material, too. Several useful substances - such as sodium, chlorine, sodium chloride, hydrogen and sodium hydroxide - can be obtained from it.

Composition of the Earth's atmosphere

air is made up of nitrogen (78%), oxygen (21%) and other gases (1%)

The composition of air

The Earth's atmosphere has remained much the same for the past 200 million years. The pie chart shows the proportions of the main gases in the atmosphere.

It is clear that the main gas is nitrogen. Oxygen - the gas that allows animals and plants to respire [respire: To engage in respiration - the energy-producing process inside living cells ], and fuels to burn - is the next most abundant gas. These two gases are both elementselements: All atoms of an element have the same atomic number, the same number of protons and electrons, and so the same chemical properties., and they account for about 99% of the gases in the atmosphere. The remaining gases - such as carbon dioxide, water vapour and noble gases such as argon - are found in much smaller proportions.

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