1Summary: Chapter 1 Cambridge University Press IGCSE Chemistry

Chapter 1SummaryYou should know that:

there are important natural cycles that involve the movement of resources within the Earths ecology!three such cycles are the water cycle and the carbon and nitrogen cycles!the air is composed predominantly of nitrogen and oxygen, but other gases have major roles to play too!the atmosphere can be polluted by human activities. There are several major atmospheric pollution problems that are changing !the nature of our world: acid rain and photochemical smog in our cities are among these.the availability of clean, fresh water is one of the major problems in the world.!we have systems for cleaning water for domestic and industrial use, and for treatment of water after its use in order to recycle it!mineral ores and crude oil provide sources of metals and chemicals for industrial use!limestone is an example of one of these mineral resources that has a range of uses; from the making of cement and concrete to !the extractionof iron in the blast furnacenatural resources can be classed as renewable or non-renewable!currently we are very dependent on fossil fuels as the source of our energy supply!there are various alternative energy sources that are available for development: solar power, wind power, hydroelectric and !nuclear power being among themone energy source currently under development is the use of hydrogen!the use of hydrogen is seen as being an environmentally clean source as the only product of its combustion is water!

! the gases of the air can be separated by the fractional distillation of liquid air, and the separated gases have their own usesglobal warming is a further atmospheric problem facing the world. The climate changes resulting from this are a major area of !concern. Global warming is caused by an increase in the atmosphere of certain greenhouse gases such as carbon dioxide and methane.the most advanced area of development for hydrogen as an energy source is as an alternative to petrol (gasoline) in cars!the hydrogen fuel cell can be used to power cars!the hydrogen fuel cell is based on the production of electrical power using the combustion reaction for hydrogen.!

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